Textbook-Integrated Guide to Educational Resources

TIGER

A Dramatic Classroom Demonstration of Limiting Reagent Using the Vinegar and Sodium Hydrogen Carbonate ReactionRomklao Artdej and Tienthong ThongpanchangThis demonstration, appropriate for high school chemistry level and recommended for a large classroom presentation, is designed to illustrate the concept of limiting reagent via a series of experiments in which increasing amounts of sodium bicarbonate are added to a fixed amount of vinegar is fixed until the volume of carbon dioxide generated remains constant. Artdej, Romklao; Thongpanchang, Tienthong. J. Chem. Educ.2008, 85, 1382.

Helping Students Assess the Relative Importance of Different Intermolecular InteractionsPaul G. JasienA semi-quantitative model has been developed to estimate the relative effects of dispersion, dipoledipole interactions, and H-bonding on the normal boiling points for a series of simple, straight-chain organic compounds. Application of this model may be useful in addressing student misconceptions related to the additivity of intermolecular interactions.Jasien, Paul G. J. Chem. Educ.2008, 85, 1222.

Determination of the Formula of a Hydrate: A Greener AlternativeMarc A. Klingshirn, Allison F. Wyatt, Robert M. Hanson, and Gary O. SpessardThis article describes how the principles of green chemistry were applied to a first-semester, general chemistry courses, specifically in relation to the determination of the formula of a copper hydrate salt that changes color when dehydrated and is easily rehydrated with steam.Klingshirn, Marc A.; Wyatt, Allison F.; Hanson, Robert M.; Spessard, Gary O. J. Chem. Educ.2008, 85, 819.

Gravimetric Analysis |

Green Chemistry |

Solids |

Stoichiometry

A Simple Penny AnalysisNicholas C. Thomas and Stephen FaulkDescribes a simple procedure for determining the zinc composition of U.S. pennies in which the penny zinc core is dissolved in acid and the evolved hydrogen gas is collected by water displacement.Thomas, Nicholas C.; Faulk, Stephen. J. Chem. Educ.2008, 85, 817.

Yet Another Variation on the Electrolysis of Water at Iron NailsMark T. Stauffer and Justin P. FoxDescribes a variation on the electrolysis of water with iron nails in which a sharp contrast in the colors produced effectively demonstrates electrolysis and the diffusion of oxidized and reduced species from the electrodes.Stauffer, Mark T.; Fox, Justin P. J. Chem. Educ.2008, 85, 523.

Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry LaboratoryKristen L. Cacciatore, Jose Amado, Jason J. Evans, and Hannah SevianPresents a novel first-year chemistry experiment that asks students to replicate procedures described in sample lab reports that lack essential information. This structure is designed to promote students' experimental design and data analysis skills as well as their understanding of the importance and essential qualities of written and verbal communication between scientists.Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah. J. Chem. Educ.2008, 85, 251.

Equilibrium |

Green Chemistry |

Periodicity / Periodic Table |

Solutions / Solvents |

Stoichiometry |

Titration / Volumetric Analysis

Scientific–Chemical Viewpoints Regarding Smoking: A Science Laboratory for AllRon BlonderThis article describes a lab that examines the acidity of cigarette smoke as well as solid particles and vapor phase substances found therein, and simulates the effects of smoking on the lungs. The aim of this activity is to expose adolescents to the scientific aspects of smoking and the relevance of chemistry in everyday life.Blonder, Ron. J. Chem. Educ.2008, 85, 248.

A Simplified Model To Predict the Effect of Increasing Atmospheric CO2 on Carbonate Chemistry in the OceanBrian J. Bozlee, Maria Janebo, and Ginger JahnThe chemistry of dissolved inorganic carbon in seawater is reviewed and used to predict the potential effect of rising levels of carbon dioxide in the atmosphere. It is found that calcium carbonate may become unsaturated in cold surface seawater by the year 2100, resulting in the destruction of calcifying organisms such as coral.Bozlee, Brian J.; Janebo, Maria; Jahn, Ginger. J. Chem. Educ.2008, 85, 213.

Applications of Chemistry |

Aqueous Solution Chemistry |

Atmospheric Chemistry |

Equilibrium |

Green Chemistry |

Water / Water Chemistry

Reaction Order Ambiguity in Integrated Rate PlotsJoe LeeThis article provides a theoretical and statistical justification for the necessity of monitoring a reaction to a substantial fraction of completion if integrated rate plots plots are to yield unambiguous orders.Lee, Joe. J. Chem. Educ.2008, 85, 141.

Experimental Determination of Ultraviolet Radiation Protection of Common MaterialsSusana C. A. Tavares, Joaquim C. G. Esteves de Silva, and João PaivaThe oxidation of iodide is used as an indicator for the degree of exposure to UV radiation and to investigate the protection given by a simulation of ozone using plexiglass plates, sunscreen lotions, cotton cloth with different colors, and aqueous solutions with different concentrations of natural organic matter.Tavares, Susana C. A.; Esteves de Silva, Joaquim C. G.; Paiva, João. J. Chem. Educ.2007, 84, 1963.

How Many Atomic Layers of Zinc Are in a Galvanized Iron Coating? Shui-Ping YangThis article describes a guided inquiry and problem solving experiment in which students use a novel gasometric assembly to determine the thickness and number of atomic layers of zinc coating on galvanized iron wires and nails.Yang, Shui-Ping. J. Chem. Educ.2007, 84, 1792.

Aqueous Solution Chemistry |

Consumer Chemistry |

Electrochemistry |

Gases |

Laboratory Equipment / Apparatus |

Quantitative Analysis |

Rate Law

Concept Maps for General Chemistry Boyd L. EarlTwo concept maps have been developed to represent the organization of the material in a first-semester general chemistry course. By providing these maps to students and referring to them in class, it is hoped that the instructor can assist students in maintaining a grasp of the "big picture" during the progress of the course.Earl, Boyd L. J. Chem. Educ.2007, 84, 1788.

Geographical Information Systems (GIS) Mapping of Environmental Samples across College CampusesKathleen L. Purvis-Roberts, Harriet P. Moeur, and Andrew ZanellaIn this laboratory experiment, students take environmental samples (concentrations of nitrogen dioxide) and geospatial coordinates with a global position systems unit at various locations around campus, map their data on a geo-referenced map with geographical information systems software, and compare their results to those observed by governmental agencies.Purvis-Roberts, Kathleen L.; Moeur, Harriet P.; Zanella, Andrew. J. Chem. Educ.2007, 84, 1691.

Applications of Chemistry |

Atmospheric Chemistry |

Gases |

Laboratory Computing / Interfacing |

UV-Vis Spectroscopy

A Simple Calorimetric Experiment That Highlights Aspects of Global Heat Retention and Global WarmingJoel D. Burley and Harold S. JohnstonIn this laboratory experiment, general chemistry students verify that heat is consumed in the melting of ice, with no increase in temperature until all the ice has melted. The fundamental calorimetric principles demonstrated by the lab results are then developed to help students better assess and understand the experimental evidence associated with global warming.Burley, Joel D.; Johnston, Harold S. J. Chem. Educ.2007, 84, 1686.

Atmospheric Chemistry |

Calorimetry / Thermochemistry

Carbon Dioxide FountainSeong-Joo Kang and Eun-Hee RyuThis article presents the development of a carbon dioxide fountain that, unlike the traditional ammonia fountain, is odorless and uses consumer chemicals. This experiment also allows students to see evidence of a gaseous reagent being consumed when a pressure sensor is available.Kang, Seong-Joo; Ryu, Eun-Hee. J. Chem. Educ.2007, 84, 1671.

Acids / Bases |

Consumer Chemistry |

Gases |

Laboratory Equipment / Apparatus |

Reactions

A Fast Coulometric Estimation of Avogadro's NumberNicholas C. ThomasUsing simple materials found in any high school or college laboratory, an electrochemical method of determining Avogadro's number is presented.Thomas, Nicholas C. J. Chem. Educ.2007, 84, 1667.

Electrochemistry |

Gases

The Use of Limits in an Advanced Placement Chemistry CoursePaul S. Matsumoto, Jonathan Ring, and Jia Li (Lily) ZhuThis article describes the use of limits in topics usually covered in advanced placement or first-year college chemistry. This approach supplements the interpretation of the graph of an equation since it is usually easier to evaluate the limit of a function than to generate its graph.Matsumoto, Paul S.; Ring, Jonathan; Zhu, Jia Li (Lily). J. Chem. Educ.2007, 84, 1655.

Exception to the Le Châtelier PrincipleThomas R. HerrintonDisagreement regarding an apparent exception to the Le Chtelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Herrinton, Thomas R. J. Chem. Educ.2007, 84, 1427.

Equilibrium |

Gases

Exception to the Le Châtelier PrincipleThomas R. HerrintonDisagreement regarding an apparent exception to the Le Chatelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Herrinton, Thomas R. J. Chem. Educ.2007, 84, 1427.

Equilibrium |

Gases

Lewis Structure Representation of Free Radicals Similar to ClOWarren Hirsch and Mark KobrakAn unconventional Lewis structure is proposed to explain the properties of the free radical ClO and a series of its isoelectronic analogues, particularly trends in the spin density of these species. Hirsch, Warren; Kobrak, Mark. J. Chem. Educ.2007, 84, 1360.

Atmospheric Chemistry |

Computational Chemistry |

Covalent Bonding |

Free Radicals |

Lewis Structures |

Molecular Modeling |

MO Theory |

Valence Bond Theory

Guitar Strings as Standing Waves: A DemonstrationMichael DavisThis demonstration uses an acoustic guitar to produce three unique harmonic vibrations, each of which is representative of a standing wave and illustrates the concept of quantization.Davis, Michael. J. Chem. Educ.2007, 84, 1287.

What Are Students Thinking When They Pick Their Answer?Michael J. Sanger and Amy J. Phelps330 students were asked to answer a multiple-choice question concerning gas properties at the microscopic level and explain their reasoning. Of those who selected the correct answer, 80% provided explanations consistent with the scientifically accepted answer, while 90% of the students who picked an incorrect choice provided explanations with at least one misconception.Sanger, Michael J.; Phelps, Amy J. J. Chem. Educ.2007, 84, 870.

Gases |

Kinetic-Molecular Theory |

Phases / Phase Transitions / Diagrams |

Qualitative Analysis

Enthalpy of Vaporization and Vapor Pressures: An Inexpensive ApparatusRubin Battino, David A. Dolson, Michael R. Hall, and Trevor M. LetcherDescribes an inexpensive apparatus for the determination of the vapor pressure of a liquid as a function of temperature for the purpose of calculating enthalpy changes of vaporization. Also described are a simple air thermostat and an inexpensive temperature controller based on an integrated temperature sensor.Battino, Rubin; Dolson, David A.; Hall, Michael R.; Letcher, Trevor M. J. Chem. Educ.2007, 84, 822.

Where Did the Water Go? Boyle's Law and Pressurized Diaphragm Water TanksJames Brimhall and Sundar NagaBoyles law (PV is constant) provides mathematical insight into the workings of pressurized diaphragm tanks for storage of water pumped from underground wells, including predictions of the quantities of available water resulting from different initial conditions of water tank systems.Brimhall, James; Naga, Sundar. J. Chem. Educ.2007, 84, 425.

Thermochemical Analysis of Neutralization Reactions: An Introductory Discovery ExperimentKenneth V. Mills and Louise W. GuilmetteDescribes a guided-inquiry laboratory pedagogy in which students discover chemical concepts in the lab and the instructor uses their pooled data to guide the lecture portion of the course. This method is illustrated by an experiment that reinforces students' understanding of stoichiometry and allows them to discover neutralization reactions and thermochemistry.Mills, Kenneth V.; Guilmette, Louise W. J. Chem. Educ.2007, 84, 326.

Response to "Keeping Our Cool"Roy W. ClarkGeneral chemistry teachers should teach general chemistry. They should teach neither the appreciation of the wonders of modern science, nor should they teach the evil consequences of modern science.Clark, Roy W. J. Chem. Educ.2007, 84, 232.

Job's Analysis of the Range of the "Dalton Syringe Rocket"Natalie Barto, Brandon Henrie, and Ed VitzAn apparatus for safely igniting fuel gas/oxygen mixtures in a syringe and measuring the distance that the syringe is propelled is presented. The distance (range) is analyzed by the method of continuous variation (Job's Method) to determine the stoichiometry of the reaction.Barto, Natalie; Henrie, Brandon; Vitz, Ed. J. Chem. Educ.2006, 83, 1505.

Gases |

Oxidation / Reduction |

Thermodynamics |

Stoichiometry

Teaching Physical Chemistry Experiments with a Computer Simulation by LabVIEWA. Belletti, R. Borromei, and G. InglettoThis article reports on a computer simulation developed with the software LabVIEW of the physical chemistry experiment regarding the vapor pressure measurements of a pure liquid as a function of temperature, as well as a system of data collecting that emphasizes the similarities between the virtual and real experiment.Belletti, A.; Borromei, R.; Ingletto, G. J. Chem. Educ.2006, 83, 1353.

Equilibrium |

Laboratory Computing / Interfacing |

Liquids |

Thermodynamics |

Gases |

Student-Centered Learning

A Laboratory Experiment Using Molecular Models for an Introductory Chemistry ClassShahrokh GhaffariPresents a new approach to using molecular models in teaching general chemistry concepts. Students construct molecular models and use them to balance simple chemical equations, demonstrate the law of conservation of mass, and discover the relationship between the mole and molecules and atoms.Ghaffari, Shahrokh. J. Chem. Educ.2006, 83, 1182.

Molecular Modeling |

Stoichiometry |

Student-Centered Learning

Two "Gas-in-a-Bag" Reactions To Show the Predictive Power of the Relative AcidBase Strength ChartBrett CriswellDescribes a demonstration in which two different pairs of solid chemicals mixed in two different Ziploc bags in the presence of a small quantities of water react to produce gases. Students are informed that the reactions are BrnstedLowry acidbase type reactions and must determine which member in each pair will act as the acid and which as the base.Criswell, Brett. J. Chem. Educ.2006, 83, 1167.

Stoichiometry of Calcium MedicinesGabriel PintoCalcium supplements provide an excellent context in which to review most of the core content of general chemistry, namely, stoichiometry, concentration units, hydration of salts, inorganic and organic salts, physiological importance of elements, resonance in ions, geometry of polyatomic ions, and isomerism.Pinto, Gabriel. J. Chem. Educ.2005, 82, 1509.

Stoichiometry |

Applications of Chemistry |

Drugs / Pharmaceuticals |

Medicinal Chemistry

Gas Permeability of PolymersJee-Yon LeeUndergraduate students can learn what causes the helium-inflated balloon to fall in a few days through the proposed experiment.Lee, Jee-Yon. J. Chem. Educ.2005, 82, 1472.

Gases |

Transport Properties

Gas Permeability of PolymersBruno LunelliThe recent article, Applying Chemical Potential and Partial Pressure Concepts To Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon, proposes a model of permeation untenable and in contradiction with correct statements present in the same text and consequently does not consider the material of which the investigated balloons are made.Lunelli, Bruno. J. Chem. Educ.2005, 82, 1471.

Gases |

Transport Properties

Gas Permeability of PolymersBruno LunelliBy studying a number of soft drinks with color but with or without phosphoric acid, the authors have determined that the required 20-fold dilution required in the Determination of Phosphorus in Cola Drinks is not to dilute the color but merely to place the sample within the calibration range of the analysis.Lunelli, Bruno. J. Chem. Educ.2005, 82, 1471.

Assessing the Effect of Web-Based Learning Tools on Student Understanding of Stoichiometry Using Knowledge Space TheoryRamesh D. Arasasingham, Mare Taagepera, Frank Potter, Ingrid Martorell, and Stacy LonjersThis paper reports a comparative study using knowledge space theory (KST) to assess the impact of a Web-based instructional software program on students' understanding of the concept of stoichiometry. The software program called Mastering Chemistry Web (MCWeb) allows students to practice problems that emphasize the development of molecular-level conceptualization and visualization, analytical reasoning, and proportional reasoning, as well as learning to recognize and relate different representations in chemistry. The experimental design compared students in two sections taught by the same instructor. One section used the MCWeb instructional software as homework (MCWeb group) while the other section used text-based homework (non-MCWeb group, control). Arasasingham, Ramesh D.; Taagepera, Mare; Potter, Frank; Martorell, Ingrid; Lonjers, Stacy. J. Chem. Educ.2005, 82, 1251.

Stoichiometry |

Student-Centered Learning

A Passive Sampler for Determination of Nitrogen Dioxide in Ambient AirDan Xiao, Lianzhi Lin, Hongyan Yuan, Martin M. F. Choi, and Winghong ChanThis article describes the use of a passive sampler for detecting and collecting nitrogen dioxide, NO2, in ambient air. This device is based on microporous PTFE membranes that allow air samples to diffuse through and subsequently react with an absorbing reagent solution. The absorbance value of this reagent is proportional to the NO2 concentration in ambient air. It has been successfully applied to determine the NO2 concentrations in various sampling sites.Xiao, Dan; Lin, Lianzhi; Yuan, Hongyan; Choi, Martin M. F.; Chan, Winghong. J. Chem. Educ.2005, 82, 1231.

Calibration |

Membranes |

UV-Vis Spectroscopy |

Amines / Ammonium Compounds |

Coordination Compounds |

Gases |

Laboratory Equipment / Apparatus |

Nonmajor Courses |

Quantitative Analysis

Mass Relationships in a Chemical Reaction: Incorporating Additional Graphing Exercises into the Introductory Chemistry LaboratoryStephen DeMeoThe purpose of this article is to increase student involvement with graph construction specifically in the context of introductory laboratory activities that involve mass relationships between reacting substances and products. In this regard, five massmass plots derived from a synthesis of a binary compound from its elements are presented as well as a set of questions to focus learners on the significance of each plot. The benefit of providing learners with these types of graphing activities include the use of higher-order cognitive processes as well as the elucidation of fundamental chemical knowledge such as the law of the conservation of mass, the law of constant composition, limiting and excess reactants, and empirical formula.DeMeo, Stephen. J. Chem. Educ.2005, 82, 1219.

Stoichiometry |

Oxidation / Reduction |

Reactions |

Quantitative Analysis

A Note on Dalton's Law: Myths, Facts, and ImplementationRonald W. Missen and William R. SmithThe treatment of Dalton's law for gas mixtures commonly includes the improper designation "Dalton's law of partial pressures", rather than the correct "Dalton's law of additivity of (pure component) pressures". It also identifies the pure component pressure as the partial pressure, although these are only numerically equal for a mixture of ideal gases. The situation is clarified by examination of an appropriate statement of the law and definitions, eventually in operational form with reference to mixtures of nonideal gases.Missen, Ronald Wi.; Smith, William R. J. Chem. Educ.2005, 82, 1197.

Thermodynamics |

Gases

Some Insights Regarding a Popular Introductory Gas Law ExperimentEd DePierro and Fred GarafaloThis paper alerts readers to a potential source of error in one approach to the Dumas method as it is often practiced in introductory chemistry laboratories. The room-temperature vapor pressures of volatile compounds that might be considered as unknowns for the experiment lead to determined molar masses that are too low. The greater the vapor pressure of the compound, the lower the determined molar mass will be, when compared to the accepted value. DePierro, Ed; Garafalo, Fred. J. Chem. Educ.2005, 82, 1194.

Gases |

Laboratory Equipment / Apparatus |

Phases / Phase Transitions / Diagrams |

Physical Properties

Cross-Proportions: A Conceptual Method for Developing Quantitative Problem-Solving SkillsElzbieta Cook and Robert L. CookThis paper focuses attention on the cross-proportion (C-P) method of mathematical problem solving, which was once widely used in chemical calculations. We propose that this method regain currency as an alternative to the dimensional analysis (DA) method, particularly in lower-level chemistry courses. In recent years, the DA method has emerged as the only problem solving mechanism offered to high-school and general chemistry students in contemporary textbooks, replacing more conceptual methods, C-P included. Cook, Elzbieta; Cook, Robert L. J. Chem. Educ.2005, 82, 1187.

Learning Theories |

Stoichiometry |

Chemometrics |

Student-Centered Learning

Steel Wool and Oxygen: A Look at KineticsJames Gordon and Katherine ChanceyAn experimental method is described to study the kinetics of the reaction of the iron in steel wool with molecular oxygen. A calculator-based data collection system is used with an oxygen gas sensor to determine the order of the reaction with respect to oxygen. Using the graphical method, students determine that the reaction follows first-order kinetics with respect to oxygen. Gordon, James; Chancey, Katherine. J. Chem. Educ.2005, 82, 1065.

Atmospheric Chemistry |

Gases |

Kinetics |

Oxidation / Reduction

Greenhouse Gases and Non-gray BehaviorJ. C. JonesGreenhouse gases feature in many courses in applied chemistry as well as in courses on environmental science, atmospheric chemistry, and so on. We hear a great deal about such matters from the media. A more classical topic which first-year chemistry students will learn about in the physical chemistry component of their program is the black body concept and the StefanBoltzmann law. Recently in teaching about greenhouse gases to MSc students I have thought of a link between the topical and classical matters that is pedagogically interesting and might be of value to others teaching in this subject area.Jones, J. C. J. Chem. Educ.2005, 82, 837.

Atmospheric Chemistry |

Gases

Analysis of OxiClean: An Interesting Comparison of Percarbonate Stain RemoversJeffrey D. Bracken and David TietzSeveral different brands of oxygen-based multipurpose stain removers consist of simple mixtures of sodium percarbonate and sodium carbonate. A small sample of each brand of stain remover is decomposed and then analyzed. The observed difference in mass allows students to accurately determine the percentages of each component of the stain remover. A back-titration experiment and a precipitation reaction are performed to confirm the complete decomposition of the original mixture.Bracken, Jeffrey D.; Tietz, David. J. Chem. Educ.2005, 82, 762.

Stoichiometry |

Consumer Chemistry

Procedure for Decomposing a Redox Reaction into Half-ReactionsIlie Fishtik and Ladislav H. BerkaThe principle of stoichiometric uniqueness provides a simple algorithm to check whether a simple redox reaction may be uniquely decomposed into half-reactions in a single way. For complex redox reactions the approach permits a complete enumeration of a finite and unique number of ways a redox reaction may be decomposed into half-reactions. Several examples are given. Fishtik, Ilie; Berka, Ladislav H. J. Chem. Educ.2005, 82, 553.

Stoichiometry |

Equilibrium |

Electrochemistry |

Oxidation / Reduction |

Reactions |

Thermodynamics

The Reaction Quotient Is Unnecessary To Solve Equilibrium ProblemsPaul S. MatsumotoThe traditional method to determine the equilibrium concentration of chemicals in a reaction, given the equilibrium constant and the initial concentration of chemicals in the reaction, involves the determination of the reaction quotient. This article will demonstrate that this step may be eliminated; thereby simplifying the algorithm to solve such problems. Such a reduction in the complexity of the algorithm may result in more students successfully being able to solve such problems. Matsumoto, Paul S. J. Chem. Educ.2005, 82, 406.

Equilibrium |

Learning Theories |

Chemometrics

Applying Chemical Potential and Partial Pressure Concepts To Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated BalloonJee-Yon Lee, Hee-Soo Yoo, Jong Sook Park, Kwang-Jin Hwang, and Jin Seog KimIn developing this laboratory, our initial motivation for the analysis of gases in a balloon was to answer simple and basic questions, such as, Why does a helium-charged balloon left in the air always drop in a few days? Is leakage of helium the only cause of the drop? What is the composition of the gas in the balloon when it falls after deflation? Students were intrigued by these questions, too, as they analyzed the variation over time in the composition in a balloon inflated with helium. Using the concepts of partial pressure and chemical potential, the laboratory experiment described effectively investigates the diffusion process and the behavior of gas molecules for teaching these concepts in general and physical chemistry. Lee, Jee-Yon; Yoo, Hee-Soo; Park, Jong Sook; Hwang, Kwang-Jin; Kim, Jin Seog. J. Chem. Educ.2005, 82, 288.

Transport Properties |

Gases |

Mass Spectrometry |

Quantitative Analysis

The Determination of the Percent of Oxygen in Air Using a Gas Pressure SensorJames Gordon and Katherine ChanceyA new detection method is applied to a classic experiment in which gaseous atmospheric oxygen in a test tube is reacted with the iron in steel wool to produce rust. A gas pressure sensor interfaced to a calculator-based data collection system was used to measure the percent of oxygen in the air as the reaction proceeded. The results from the calculator-based experiment were compared to the results from a more traditional water-measurement experiment. The average percent of oxygen obtained using the calculator system was 19.4  0.4%. Gordon, James; Chancey, Katherine. J. Chem. Educ.2005, 82, 286.

Atmospheric Chemistry |

Gases |

Oxidation / Reduction |

Reactions

Fractional Distillation of Air and Other Demonstrations with Condensed GasesMaria Oliver-Hoyo and William L. Switzer, IIIThis demonstration builds upon the commonly performed liquefaction of air not only to show the presence of nitrogen and oxygen, but also the presence of two other components, carbon dioxide and water. Several extensions are suggested: one to show boiling point elevation in solution and another to show the elevation of both boiling point and sublimation point with pressure. No special apparatus is required permitting presentations to audiences in a variety of settings. These demonstrations give the opportunity to discuss properties of gases, solution chemistry, and phase equilibria.Oliver-Hoyo, Maria; Switzer, William L., III. J. Chem. Educ.2005, 82, 251.

Gases |

Qualitative Analysis |

Atmospheric Chemistry |

Phases / Phase Transitions / Diagrams |

Separation Science

A Methane Balloon Inflation ChamberCurtis J. Czerwinski and Tanya J. CordesWhile several lecture demonstrations are possible using methane-filled balloons, it is often inconvenient to prepare these balloons since the pressure from standard laboratory and lecture hall gas nozzles is too low. As a solution to this problem, a methane balloon inflation chamber, prepared from a translucent 3.5-gallon pail and an aspirator or house-vacuum, provides an inexpensive and convenient method for inflating balloons in laboratories or lecture halls. Prepared in this way, methane-filled balloons can be used to demonstrate the effects of vacuum, the lifting power of low-density gases, and the explosive combustion of methane. Czerwinski, Curtis J.; Cordes, Tanya J. J. Chem. Educ.2005, 82, 248.

Alkanes / Cycloalkanes |

Calorimetry / Thermochemistry |

Gases |

Oxidation / Reduction |

Reactions

On the Buoyancy of a Helium-Filled BalloonJohn E. HarrimanIt is shown by expansion of the exponential in the barometric formula that the forces due to pressure acting on a balloon are of the form (PV/RT)Mg and that results agree with those suggested by Archimedes principle. Einstein's equivalence principal provides an answer to what balloons will do in an accelerated car. Harriman, John E. J. Chem. Educ.2005, 82, 246.

Atmospheric Chemistry |

Gases |

Kinetic-Molecular Theory |

Physical Properties

Evaluating Students' Conceptual Understanding of Balanced Equations and Stoichiometric Ratios Using a Particulate DrawingMichael J. SangerA total of 156 students were asked to provide free-response balanced chemical equations for a classic multiple-choice particulate-drawing question first used by Nurrenbern and Pickering. The balanced equations and the number of students providing each equation are reported in this study. The most common student errors included a confusion between the concepts of subscripts and coefficients and including unreacted chemical species in the equation. Sanger, Michael J. J. Chem. Educ.2005, 82, 131.

Stoichiometry |

Kinetic-Molecular Theory

Capillary Electrophoresis Analysis of Cations in Water Samples. An Experiment for the Introductory LaboratoryChristopher J. Pursell, Bert Chandler, and Michelle M. BusheyThis experiment can be done in a lab, as a "dry-lab", or as an in-class exercise. Students explore a number of basic separation topics and work with figures of merit for real and meaningful samples. We have adopted a strategy where students encounter various instruments and methods of analyses multiple times throughout the curriculum. The level of sophistication in the exposures increases with the experience level of the students. Through this repeated exposure students will gain a better and fuller understanding of these methods than they would with a single exposure to the technique in the analytical or instrumental laboratory. Pursell, Christopher J.; Chandler, Bert; Bushey, Michelle M. J. Chem. Educ.2004, 81, 1783.

Electrophoresis |

Quantitative Analysis |

Separation Science |

Chemometrics |

Water / Water Chemistry

Empirical Formulas and the Solid State: A ProposalWilliam B. JensenThis brief article calls attention to the failure of most introductory textbooks to point out explicitly the fact that nonmolecular solids do not have molecular formulas and suggests some practical remedies for improving textbook coverage of this subject. The inadequacies of the terms "empirical formula" and "molecular formula" are also discussed, and the terms "relative compositional formula" and "absolute compositional formula" are proposed as more appropriate alternatives. Jensen, William B. J. Chem. Educ.2004, 81, 1772.

Solid State Chemistry |

Solids |

Stoichiometry |

Nomenclature / Units / Symbols

Statistical Comparison of Data in the Analytical LaboratoryMichael J. SamideIn this article, an experiment designed to provide students with an experience involving statistical treatment of data is described. This experiment allows students to compare 11 different techniques for measuring specific volumes of water. Replicate measurements are taken for each technique and comparisons are made both within a data set and between different data sets. Through calculation of t-values, students are able to draw conclusions about the precision and accuracy of these various techniques.Samide, Michael J. J. Chem. Educ.2004, 81, 1641.

Campbell's Rule for Estimating Entropy ChangesWilliam B. JensenIn a recent article Norman Craig has proposed the rule-of-thumb that the approximate value of the entropy of reaction is related to the net moles of gas consumed or generated in the reaction .Jensen, William B. J. Chem. Educ.2004, 81, 1570.

Gases |

Thermodynamics

Using Knowledge Space Theory To Assess Student Understanding of StoichiometryRamesh D. Arasasingham, Mare Taagepera, Frank Potter, and Stacy LonjersUsing the concept of stoichiometry we examined the ability of beginning college chemistry students to make connections among the molecular, symbolic, and graphical representations of chemical phenomena, as well as to conceptualize, visualize, and solve numerical problems. Students took a test designed to follow conceptual development; we then analyzed student responses and the connectivities of their responses, or the cognitive organization of the material or thinking patterns, applying knowledge space theory (KST). The results reveal that the students' logical frameworks of conceptual understanding were very weak and lacked an integrated understanding of some of the fundamental aspects of chemical reactivity. Arasasingham, Ramesh D.; Taagepera, Mare; Potter, Frank; Lonjers, Stacy. J. Chem. Educ.2004, 81, 1517.

Learning Theories |

Stoichiometry |

Constructivism

The Origin of the Mole ConceptWilliam B. JensenIn response to a reader query, the column traces the origins of the mole concept in chemistry. Jensen, William B. J. Chem. Educ.2004, 81, 1409.

Stoichiometry |

Nomenclature / Units / Symbols

Unified Approximations: A New Approach for Monoprotic Weak Acid–Base EquilibriaHarry L. Pardue, Ihab N. Odeh, and Teweldemedhin M. TesfaiThis article describes a new approach to approximate calculations for monoprotic acidbase equilibria in otherwise pure water. The new approach, identified herein as unified approximations, uses a simple decision criterion to select between situations that should be treated as deprotonation and protonation reactions. The remaining treatment takes account of changes in concentrations of conjugate acidbase pairs for all situations and ignores autoprotolysis only for situations for which the analytical concentration of either the conjugate acid or conjugate base will always be larger than zero. Pardue, Harry L.; Odeh, Ihab N.; Tesfai, Teweldemedhin M. J. Chem. Educ.2004, 81, 1367.

Acids / Bases |

Equilibrium |

Chemometrics

Construction of a Small-Scale and Low-Cost Gas ApparatusLise Kvittingen and Richard VerleyThis article describes how to construct an apparatus for gas production from disposable polyethene pipets and polypropene microcentrifuge tubes. Heat is used to form the plastics into appropriate shapes. A stand from floral wire is also presented. The assembly has an open interface and is possible to modify. This construction suits various grades and curricula and can easily be integrated into different topics. Kvittingen, Lise; Verley, Richard. J. Chem. Educ.2004, 81, 1339.

Laboratory Equipment / Apparatus |

Microscale Lab |

Gases

Reaction to Why Do We Teach Equilibrium Calculations?Stephen J. Hawkes"Rigor" in introductory chemistry is often equated with quantitation. Consequently the understanding of chemical reactions and properties is obscured. This was illustrated by Stumpo who asked students to calculate ?E of a reaction, and then on another question on the same test asked a question aimed at its meaning. 77% of the students calculated correctly, but only 24% showed understanding of its meaning. The ability to calculate a number does not measure understanding of the number. Hawkes, Stephen J. J. Chem. Educ.2004, 81, 1265.

Equilibrium |

Chemometrics

Reaction to Why Do We Teach Equilibrium Calculations? Don L. LewisA recently published correspondence by Stephen J. Hawkes on teaching equilibrium calculations troubles me. Hawkes dismisses equilibrium calculations as mere algorithms, best deferred until the student can use computer programs. I find it difficult to believe that a computer program enhances understanding. From a chemists point of view, the equilibrium condition is a limit, a limit that (because of stochastic considerations) does not exist. It might be better to make the reaction quotient statement using < or > but the use of those relations is delayed until quantum mechanics.Lewis, Don L. J. Chem. Educ.2004, 81, 1265.

Equilibrium |

Chemometrics

Water in the AtmosphereJoel M. KauffmanNone of eight college-level general chemistry texts gave a mean value for water in the atmosphere, despite its being the third most prevalent constituent at about 1.5% by mass as vapor and about 2% if clouds and ice crystals are included. The importance of water as a greenhouse gas was omitted or marginalized by five of the eight texts. An infrared spectrum of humid air was determined to demonstrate that water vapor, because of its higher concentration, was more absorptive than carbon dioxide. The cooling effect of clouds, or other influences on the Earth's albedo, were not mentioned in most of the texts. These pervasive errors should be corrected in new or future editions of textbooks. Kauffman, Joel M. J. Chem. Educ.2004, 81, 1229.

Atmospheric Chemistry |

Gases |

Green Chemistry |

IR Spectroscopy

Mass Spectrometry for the MassesJared D. Persinger, Geoffrey C. Hoops, and Michael J. SamideIn this article, we describe an experiment for an introductory chemistry course that incorporates the use of mass spectrometry for sample analysis. Several different air samples are collected that represent various chemical processes, and the composition of the air sample is predicted on the basis of known chemical principles. A gas chromatograph-mass spectrometer is used to analyze these samples, and the relative quantities of nitrogen, oxygen, carbon dioxide, water, and argon are calculated. On the basis of the data, the hypothesized sample composition is validated. Persinger, Jared D.; Hoops, Geoffrey C.; Samide, Michael J. J. Chem. Educ.2004, 81, 1169.

Using a Graphing Calculator To Determine a First-Order Rate Constant: Author ReplyJosé E. Cortés-FigueroaWhen technology is used to help with mathematical calculations, the emphasis must be on the concepts being learned rather than simply the procedures. In our approach we are attempting to help students learn more about the concept and also to attain data analysis skills they will need in the future. Cortés-Figueroa, José E. J. Chem. Educ.2004, 81, 485.

The Decomposition of Zinc Carbonate: Using Stoichiometry To Choose between Chemical FormulasStephen DeMeoTo determine which formula corresponds to a bottle labeled "zinc carbonate", students perform qualitative tests on three of zinc carbonate's decomposition products: zinc oxide, carbon dioxide, and water. Next students make quantitative measurements to find molar ratios and compare them with the coefficients of the balanced chemical equations. This allows the correct formula of zinc carbonate to be deduced. DeMeo, Stephen. J. Chem. Educ.2004, 81, 119.

Carbon Dioxide Flooding: A Classroom Case Study Derived from Surgical PracticeRobert C. KerberThe surgical opening in open-heart surgery is often flooded with carbon dioxide gas to avoid air embolisms when the heart is closed and restarted. This practice can be used in chemistry courses to illustrate concepts of gas density, solubility, and acidbase equilibria, including buffering.Kerber, Robert C. . J. Chem. Educ.2003, 80, 1437.

Acids / Bases |

Aqueous Solution Chemistry |

Gases |

Medicinal Chemistry |

Nonmajor Courses |

Applications of Chemistry

The Origin of Stoichiometry ProblemsWilliam B. JensenIn response to a reader query, the column discusses the question of when quantitative stoichiometry problems first began to appear in introductory textbooks, and especially the role of the American chemist, Josiah Parsons Cooke, in this process. Jensen, William B. J. Chem. Educ.2003, 80, 1248.

Stoichiometry

Why Does a Helium-Filled Balloon "Rise"?Richard W. RametteThe article is a lighthearted, conversational exploration of the microscopic basis for Archimedes principle. The principle is discussed in terms of molecular collisions and density gradients in a gravitational field. Ramette, Richard W. J. Chem. Educ.2003, 80, 1149.

SpecScan: A Utility Program for Generating Numerical Data from Printed Forms of Spectra or Other SignalsConstantinos E. EfstathiouSpecSpan is a utility program for Microsoft Windows that generates numerical data from printed spectra or other plots found as figures in text, chart recordings, or freehand drawings. SpecScan can process bitmap (.BMP) images of such figures and drawings. After a brief interaction with the user, it generates and exports numerical data as Excel (.XLS) or text (.TXT) files.Efstathiou, Constantinos E. J. Chem. Educ.2003, 80, 1093.

Determination of the Empirical Formula of a Copper Oxide Salt Using Two Different MethodsMichael J. Sanger and Kimberly GeerConverting copper oxide into copper metal using two different methods: reduction of copper oxide to copper metal using methane gas, and reduction of copper oxide to copper metal using aluminum in aqueous solution; the results are used to determine the empirical formula of copper oxide.Sanger, Michael J.; Geer, Kimberly. J. Chem. Educ.2002, 79, 994.

Just Breathe: The Oxygen Content of Air JCE Editorial StaffStudents estimate the percent oxygen (volume) in air using steel wool in a test tube that is inverted in a beaker of water. Oxygen in the trapped air reacts with iron to form rust, and the water level rises inside the test tube; within 30-45 minutes, the majority of oxygen is consumed.JCE Editorial Staff. J. Chem. Educ.2001, 78, 512A.

Electrochemistry |

Gases |

Oxidation / Reduction

Sink or Swim: The Cartesian DiverK. David PinkertonCartesian divers are a quick and simple way to illustrate relationships among pressure, volume, temperature, and buoyancy. The Activity could be used in connection with the concepts of gases and liquids and discussions of Boyle's, Charles's, and the ideal gas laws.Pinkerton, K. David. J. Chem. Educ.2001, 78, 200A.

How to Say How Much: Amounts and StoichiometryAddison AultPictorial representation of the ways by which chemists describe an amount of material, and a systematic way to create a visual representation or "map" for solving stoichiometry problems.Ault, Addison. J. Chem. Educ.2001, 78, 1347.

Determination of the Universal Gas Constant, R. A Discovery LaboratoryDavid B. Moss and Kathleen CornelyDiscovery laboratory in which groups of students collect oxygen, hydrogen, and nitrogen gas over water and determine the value of the universal gas constant, R, using the ideal gas law.Moss, David B.; Cornely, Kathleen. J. Chem. Educ.2001, 78, 1260.

"Experiment with a Candle" without a CandleDusan Krnel and Sasa A. GlazarDrawing water up into an inverted container without using the candle to demonstrate that the popular explanation for this phenomenon is flawed.Krnel, Dusan; Glazar, Sasa A. J. Chem. Educ.2001, 78, 914.

Metal Complexes of Trifluoropentanedione. An Experiment for the General Chemistry LaboratoryRobert C. Sadoski, David Shipp, and Bill DurhamInvestigation of the transition-metal complexes produced by the reactions of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) with 1,1,1-trifluoro-2,4-pentanedione; mass spectroscopy is used to determine the stoichiometry of the reaction products. Sadoski, Robert C.; Shipp, David; Durham, Bill. J. Chem. Educ.2001, 78, 665.

Coordination Compounds |

Synthesis |

Mass Spectrometry |

Transition Elements |

Stoichiometry

Analysis of an Oxygen Bleach: A Redox Titration LabChristine L. Copper and Edward KoubekStudents balance the reaction of H2O2 and MnO4 in two different ways (one assuming that H2O2 is the oxygen source and a second assuming that MnO4 is the oxygen source), determine which of these balanced equations has the correct stoichiometry by titrating a standard H2O2 solution with KMnO4, and use the correct balanced equation to determine the mass percent of H2O2 in a commercially available bleach solution. Copper, Christine L.; Koubek, Edward. J. Chem. Educ.2001, 78, 652.

What's Been Happening to Undergraduate MathematicsDavid M. BressoudAn overview of some of the changes that have been occurring in undergraduate mathematics education; based on a workshop held by the Mathematical Association of America to determine what chemists expect their students to learn from undergraduate mathematics courses in terms of understanding, content, and use of technology. Bressoud, David M. J. Chem. Educ.2001, 78, 578.

Learning Theories |

Mathematics / Symbolic Mathematics |

Chemometrics

Understanding Solubility through Excel SpreadsheetsPamela BrownThis article describes assignments related to the solubility of inorganic salts that can be given in an introductory general chemistry course. These assignments address the need for math, graphing, and computer skills in the chemical technology program by developing skill in the use of Microsoft Excel to prepare spreadsheets and graphs and to perform linear and nonlinear curve-fitting. Brown, Pamela. J. Chem. Educ.2001, 78, 268.

Aqueous Solution Chemistry |

Chemometrics |

Precipitation / Solubility

A Simple Laboratory Experiment for the Determination of Absolute ZeroMyung-Hoon Kim, Michelle Song Kim, and Suw-Young LyA novel method that employs a remarkably simple and inexpensive apparatus and is based on the extrapolation of the volume of a given amount of dry air to zero volume after a volume of air trapped inside a 10-mL graduated cylinder is measured at various temperatures.Kim, Myung-Hoon; Kim, Michelle Song; Ly, Suw-Young. J. Chem. Educ.2001, 78, 238.

Gases |

Physical Properties |

Chemometrics

The Synthesis and Analysis of Copper(I) Iodide. A First-Year Laboratory ProjectLara A. Margolis, Richard W. Schaeffer, and Claude H. YoderThis project provides a convenient preparation of a compound whose identity will not be obvious to students. The analytical procedures illustrate the fundamentals of gravimetric analysis and some basic chemical and physical characteristics of the elements. The analytical data allow students to find the identity of the product by determining its empirical formula.Margolis, Lara A.; Schaeffer, Richard W.; Yoder, Claude H. J. Chem. Educ.2001, 78, 235.

A Novel Experiment for Fast and Simple Determination of the Oxygen Content in the AirMetodija Najdoski and Vladimir M. PetrusevskiThe reaction between nitric oxide (NO) and oxygen is used for determination of the oxygen content in the air. The nitrogen dioxide thus produced is dissolved in water. The volume decrease of the gas enables quick and accurate enough determination of the O2 content. The results of 20 measurements give %O2 = 21.04  0.63. Najdoski, Metodija; Petrusevski, Vladimir M. J. Chem. Educ.2000, 77, 1447.

Potentiometric Determination of CO2 Concentration in the Gaseous Phase: Applications in Different Laboratory ActivitiesEduardo Cortón, Santiago Kocmur, Liliana Haim, and Lydia GalagovskyThe first lab comprises the calibration of a CO2 potentiometric detector with gas mixtures. The CO2 and CO2-free air required for the gaseous samples are produced in the lab by an inexpensive and simple apparatus. In the second lab, the CO2 potentiometric device is used to measure CO2 uptake and release during different metabolic processes. Cortón, Eduardo; Kocmur, Santiago; Haim, Liliana; Galagovsky, Lydia. J. Chem. Educ.2000, 77, 1188.

Electrochemistry |

Gases |

Quantitative Analysis |

Metabolism

Encouraging Meaningful Quantitative Problem SolvingJeff Cohen, Meghan Kennedy-Justice, Sunny Pai, Carmen Torres, Rick Toomey, Ed DePierro, and Fred GarafaloThis paper describes the efforts of a group of teachers to help college freshman chemistry students and high school science students to improve their problem-solving skills. The presentation includes several sets of questions intended to elucidate ideas and to involve the reader in the process of reflecting upon his or her own problem-solving strategies. Cohen, Jeff; Kennedy-Justice, Meghan; Pai, Sunny; Torres, Carmen; Toomey, Rick; DePierro, Ed; Garafalo, Fred. J. Chem. Educ.2000, 77, 1166.

Mathematics / Symbolic Mathematics |

Chemometrics

A New Approach to Teaching Introductory Science: The Gas ModulePamela Mills, William V. Sweeney, Robert Marino, and Sandra ClarksonA lecture/laboratory module about the behavior of gases that is designed to expose students to the process of scientific discovery, not to teach the gas laws per se. The topic of gases is only the medium used to illustrate other important aspects of physical science: how to process experimental data and reduce it to symbolic mathematical relationships, how to evaluate the reliability of experimental data, and how to view the relationship between experimental data and scientific models. Mills, Pamela A.; Sweeney, William V.; Marino, Robert; Clarkson, Sandra. J. Chem. Educ.2000, 77, 1161.

Gases

A Classroom Exercise in Sampling TechniqueMichael R. RossA classroom hands-on demonstration has been developed that looks at the two important sampling considerations, sample size and non-homogeneous sample materials. This classroom activity makes use of readily available M&M candies for the sample size and NERDS for the non-homogeneous sample exercises. Ross, Michael R. J. Chem. Educ.2000, 77, 1015.

Quantitative Analysis |

Chemometrics

Paradoxes, Puzzles, and Pitfalls of Incomplete Combustion DemonstrationsEd VitzPaper is burned in a closed container containing sufficient oxygen to consume all the paper. Paradoxically, the flame expires while half of the paper remains. This demonstrates that thermodynamics or stoichiometry is insufficient to explain everyday chemical processes, and that kinetics is often necessary. The gases in the container are analyzed by GC before and after combustion, and the results are examined in detail. Vitz, Ed. J. Chem. Educ.2000, 77, 1011.

Gases |

Kinetics |

Stoichiometry

A Drop in the OceanDamon DiementeTeachers of high-school chemistry customarily use calculations done as in-class exercises or as demonstrations to impress their students with the enormity of Avogadro's number and the concomitant miniscularity of atoms and molecules. This article presents and works out one such calculation. Diemente, Damon. J. Chem. Educ.2000, 77, 1010.

Determination of the Fundamental Electronic Charge via the Electrolysis of WaterBrittany Hoffman, Elizabeth Mitchell, Petra Roulhac, Marc Thomes, and Vincent M. StumpoIn an illuminating experiment suitable for secondary school students, a Hoffman electrolysis apparatus is employed to determine the fundamental electronic charge. The volume and pressure of hydrogen gas produced via the electrolysis of water during a given time interval are measured. Hoffman, Brittany; Mitchell, Elizabeth; Roulhac, Petra; Thomes, Marc; Stumpo, Vincent M. J. Chem. Educ.2000, 77, 95.

Atomic Properties / Structure |

Electrochemistry |

Gases |

Molecular Properties / Structure

The Use of Extent of Reaction in Introductory CoursesSebastian G. CanagaratnaThis article discusses the use of the extent of reaction as an alternative to the traditional approach to stoichiometry in first-year chemistry. The method focuses attention on the reaction as a whole rather than on pairs of reagents as in the traditional approach. The balanced equation is used as the unit of change. Canagaratna, Sebastian G. J. Chem. Educ.2000, 77, 52.

Stoichiometry |

Thermodynamics |

Nomenclature / Units / Symbols

Henry's Law and Noisy KnucklesDoris R. KimbroughPresented here is the application of Henry's law to the noise associated with "cracking" knuckles. Gases dissolved in the synovial fluid in joints rapidly come out of solution as the joint is stretched and pressure is decreased. This "cavitation" produces a characteristic noise. Kimbrough, Doris R. J. Chem. Educ.1999, 76, 1509.

Relative HumidityR. Bruce MartinDaily we hear reports of relative humidity, yet most students remain unfamiliar with its import. This short article defines and describes the concept at several levels. A new, general interest, isobaric plot directly indicates the dependence of relative humidity on temperature. Martin, R. Bruce. J. Chem. Educ.1999, 76, 1081.

Consumer Chemistry |

Gases |

Nonmajor Courses |

Water / Water Chemistry |

Atmospheric Chemistry

Limiting Reactant. An Alternative AnalogyZoltn TthA concrete analogy involving students and the make-up of teams is proposed to better explain the identification of the limiting reactant in stoichiometric calculations. Tth, Zoltn. J. Chem. Educ.1999, 76, 934.

Stoichiometry

The Persistence of the Candle-and-Cylinder MisconceptionJames P. Birk and Anton E. LawsonThere is a persistent misconception that when a lighted candle is supported in a container of water and a closed cylinder is lowered over the candle, the candle is extinguished after a time by complete consumption of the oxygen in the cylinder, with a volume change corresponding to the amount of oxygen in the air. This misconception has appeared in the literature periodically for many years. Here, we present a number of experiments that refute this misconception.Birk, James P.; Lawson, Anton E. J. Chem. Educ.1999, 76, 914.

The Methane BalloonWalter H. Corkern and Elvin Hughes Jr.The objectives are (i) to describe a novel method of inflating a balloon with methane, (ii) to show that methane is lighter than air, and (iii) to demonstrate the flammability of methane. Corkern, Walter H.; Hughes, Elvin, Jr. J. Chem. Educ.1999, 76, 794.

Pressure and StoichiometryCharles E. Roser and Catherine L. McCluskeyThis experiment determines the stoichiometry of the reaction of a carbonate or hydrogen carbonate and HCl by measuring the pressure of the CO2 produced using a Vernier pressure sensor, TI CBL interface, and a TI-82/83 graphing calculator. Various amounts of the carbonate are reacted with a constant amount of HCl. Roser, Charles E.; McCluskey, Catherine L. J. Chem. Educ.1999, 76, 638.

Stoichiometry |

Gases |

Laboratory Computing / Interfacing

A Demonstration of Ideal Gas Principles Using a FootballWilliam D. Bare and Lester AndrewsA class demonstration and cooperative learning activity in which the ideal gas law is applied to determine the volume of a football is described. The mass of an air-filled football is recorded at two or more pressures, and students are asked to use these data to solve problems involving the volume, pressure, and mass of the football and the molecular weight of the gas in the ball.Bare, William D.; Andrews, Lester. J. Chem. Educ.1999, 76, 622.

Gases |

Applications of Chemistry

The Ammonia Smoke Fountain: An Interesting Thermodynamic AdventureM. Dale AlexanderThe ammonia smoke fountain demonstration utilizes a modification of the apparatus used in the standard ammonia fountain. The modification allows for the introduction of hydrogen chloride gas into a flask of ammonia rather than water. The flow rate of hydrogen chloride gas into the flask in the smoke fountain is not constant, but periodic; that is, the smoke puffs from the end of the tube. This unexpected behavior elicits an interesting thermodynamic explanation.Alexander, M. Dale. J. Chem. Educ.1999, 76, 210.

Acids / Bases |

Gases |

Thermodynamics |

Reactions |

Stoichiometry |

Precipitation / Solubility

Replace Double ReplacementR. Bruce MartinReactions described as double replacements in high school texts are poorly described by this designation. The driving force for such reactions is precipitation of a solid derived from ions in solution or the production of water in acid-base reactions. Martin, R. Bruce. J. Chem. Educ.1999, 76, 133.

Stoichiometry |

Reactions |

Precipitation / Solubility

Amounts Tables as a Diagnostic Tool for Flawed Stoichiometric ReasoningJohn Olmsted IIIAmounts tables can be used to organize the data and reasoning involved in limiting-reagent problems. In this context, amounts tables can provide useful diagnostic information about students' abilities to reason stoichiometrically. Olmsted, John A., III. J. Chem. Educ.1999, 76, 52.

Learning Theories |

Stoichiometry

CHEMiCALC (4000161) and CHEMiCALC Personal Tutor (4001108), Version 4.0 (by O. Bertrand Ramsay)Scott White and George BodnerCHEMiCALC is a thoughtfully designed software package developed for use by high school and general chemistry students, who will benefit from the personal tutor mode that helps to guide them through unit conversion, empirical formula, molecular weight, reaction stoichiometry, and solution stoichiometry calculations.White, Scott; Bodner, George M. J. Chem. Educ.1999, 76, 34.

Gas Experiments with Plastic Soda BottlesPatrick Kavanah and Arden P. ZippThe construction and use of a new device to study gases is described. The device, which is made from a plastic soda bottle and an automobile tire valve, can be used to demonstrate that air has mass, find the mass of the "evacuated" device, determine the molar mass of air and other gases, investigate the pressure-volume relationship, and build a cloud chamber. Kavanah, Patrick; Zipp, Arden P. J. Chem. Educ.1998, 75, 1405.

Experimentally Determining the Molar Mass of Carbon Dioxide Using a Mylar BalloonBarbara Albers Jackson and David J. CrouseThe molar mass of carbon dioxide was experimentally determined using a Mylar balloon. Mylar balloons are lightweight, have a fixed definite volume, and require minimal additional pressure for inflation. Using the Ideal Gas Equation, the number of moles of air in the balloon was calculated. Jackson, Barbara Albers; Crouse, David J. J. Chem. Educ.1998, 75, 997.

Gases |

Physical Properties

Precision and Accuracy in Measurements: A Tale of Four Graduated CylindersRichard S. TreptowThe concepts of precision and accuracy help students understand that uncertainty accompanies even our best scientific measurements. A model experiment can be used to distinguish the two terms. The experiment uses four graduated cylinders which give measurements of different accuracy and precision. Such terms as mean, range, standard deviation, error, and true value are defined through an illustration.Treptow, Richard S. J. Chem. Educ.1998, 75, 992.

Quantitative Analysis |

Chemometrics

Percent Composition and Empirical Formula - A New ViewGeorge L. GilbertA new method of obtaining the empirical formula for a compound from its percent composition is proposed. The method involves the determination of a minimum molar mass for the compound based on the percentage of each element, obtaining the lowest common molar mass and using this data to calculate the integer values used in writing the empirical formula. Gilbert, George L. J. Chem. Educ.1998, 75, 851.

Atomic Properties / Structure |

Stoichiometry |

Chemometrics

Thermal Physics (and Some Chemistry) of the AtmosphereStephen K. LowerAn exploration of how the temperature of the atmosphere varies with altitude can serve as a useful means of illustrating some important principles relating to the behavior of gases and to the absorption and transformation of radiant energy. Lower, Stephen K. J. Chem. Educ.1998, 75, 837.

Atmospheric Chemistry |

Gases

Vapor Pressure Lowering by Nonvolatile SolutesGavin D. PeckhamThis short article highlights a fundamental error that is entrenched in introductory chemistry textbooks. It is true that the addition of a nonvolatile solute causes a lowering in the vapor pressure of a solution. The error lies in attributing this vapor pressure lowering to the "blocking" of surface sites by nonvolatile particles. This is a totally fallacious argument for a number of reasons and the true explanation is to be found in the entropy changes that occur as a nonvolatile solute is added to a solution. Peckham, Gavin D. J. Chem. Educ.1998, 75, 787.

Gases |

Solutions / Solvents |

Thermodynamics

Saving Your Students' Skin. Undergraduate Experiments that Probe UV Protection by Sunscreens and SunglassesJames R. Abney and Bethe A. ScalettarThis article describes absorption spectroscopy experiments that illustrate the mechanism of action of sunscreens and sunglasses and that highlight the differences between different products. The experiments are well suited to incorporation into an undergraduate science laboratory and will expose students to absorption phenomena in a familiar context with substantial environmental and medical relevance. Abney, James R.; Scalettar, Bethe A. J. Chem. Educ.1998, 75, 757.

Photochemistry |

UV-Vis Spectroscopy |

Atmospheric Chemistry |

Applications of Chemistry |

Spectroscopy

Photocatalytic Degradation of a Gaseous Organic PollutantJimmy C. Yu and Linda Y. L. ChanA simple and effective method to demonstrate the phenomenon of photocatalytic degradation of a gaseous organic pollutant was developed. Titanium dioxide (anatase) was used as the photocatalyst, and sunlight was found to be an effective light source for the activation of TiO2. The organic pollutant degrade in this demonstration was a common indoor air pollutant, dichloromethane.Yu, Jimmy C.; Chan, Linda Y. L. J. Chem. Educ.1998, 75, 750.

A Closer Look at the Addition of Equations and ReactionsDamon DiementeChemists occasionally find it convenient or even necessary to express an overall reaction as the sum of two or more component reactions. A close examination, however, reveals that the resemblance between chemical algebraic equations is entirely superficial, and that the real meaning of addition in chemical equations is subtle and varies from case to case. In high-school courses, students are likely to encounter the addition of equations in thermochemistry, in electrochemistry, and in kinetics. Diemente, Damon. J. Chem. Educ.1998, 75, 319.

A New and General Method for Balancing Chemical Equations by InspectionsChunshi GuoAny chemical equation, no matter how complicated, can be balanced by inspection. In fact, inspection is often the quickest and easiest way to balance complex equation. The method described here involves the use of "linked sets". It does not require the use of oxidation numbers of the splitting of equations into "half reactions". It can be used to balance all kinds of chemical equations, including ionic equations.Guo, Chunshi. J. Chem. Educ.1997, 74, 1365.

Stoichiometry

Balancing Chemical Equations by InspectionZoltán TóthThe paper shows that the balancing chemical equations by inspection is not a trial-and-error process, because a systematic procedure for the balancing simple and more complicated chemical equations without oxidation numbers or equations with several unknowns can be suggested. The proposed method is suitable for balancing all the chemical equations, including ionic equations, which have single unique solution. Toth, Zoltan. J. Chem. Educ.1997, 74, 1363.

Stoichiometry

On Balancing Chemical Equations: Past and PresentWilliam C. HerndonThe main purposes of this paper are to give a listing of selected papers on balancing chemical equations that may be useful to chemistry teachers and potential authors as background material, and to provide some comparisons of methods. The selection criteria for the references were deliberately broad, in order to include a wide variety of topics and seminal historical citations, and the references are annotated to increase their usefulness.Herndon, William C. J. Chem. Educ.1997, 74, 1359.

Formation and Dimerization of NO2 A General Chemistry ExperimentApril D. Hennis, C. Scott Highberger, and Serge Schreiner*A general chemistry experiment which illustrates Gay-Lussac's law of combining volumes. Students are able to determine the partial pressures and equilibrium constant for the formation and dimerization of NO2. The experiment readily provides students with data that can be manipulated with a common spreadsheet. Hennis, April D.; Highberger, C. Scott; Schreiner, Serge. J. Chem. Educ.1997, 74, 1340.

Gases |

Equilibrium |

Quantitative Analysis |

Stoichiometry

A Note on Covariance in Propagation of UncertaintyEdwin F. MeyerIt is pointed out that whenever both the slope and the intercept are used in calculating a physical quantity from a linear regression, propagation of error must include the covariance as well as the variances. The point is illustrated with a calculation of the boiling point of water from the parameters of the lnP vs 1/T fit. If the covariance is omitted from the propagation of error, the estimate of uncertainty is unreasonably large. Meyer, Edwin F. J. Chem. Educ.1997, 74, 1339.

Chemometrics

How Big Is the Balloon? Stoichiometry Using Baking Soda and VinegarStudents discover the concept of stoichiometry and limiting reactants in two ways: first by adding vinegar to a small quantity of baking soda until bubbles stop, and second by mixing a constant quantity of baking soda with increasing volumes of vinegar and collecting the carbon dioxide produced in balloons.J. Chem. Educ.1997, 74, 1328A.

Graham's Law and Perpetuation of ErrorStephen J. HawkesGrahams Laws of effusion and diffusion are used in recent articles for traditional experiments to which they do not in fact apply and for which they give the wrong answer.Hawkes, Stephen J. J. Chem. Educ.1997, 74, 1069.

Chemical BehaviorPaul G. JasienIn order to increase student understanding of the seemingly confusing behavior of chemical substances involved in environmental chemistry, an analogy between chemical and human behavior is presented. The analogy focuses on how the same individual can behave differently due to his/her social surroundings.Jasien, Paul G. J. Chem. Educ.1997, 74, 943.

An Analysis of the Algebraic Method for Balancing Chemical ReactionsJohn A. OlsonA new aspect of this treatment is the mathematical formulation of a third condition involving a balance between oxidation and reduction. The treatment begins with the three general conditions that a balanced chemical reaction must satisfy. These conditions are then expressed in mathematical form that enables the stoichiometric coefficients to be determined.Olson, John A. . J. Chem. Educ.1997, 74, 538.

Oxidation / Reduction |

Stoichiometry

A U-Tube Experiment To Discover the Curve in Boyle's LawThomas G. Richmond and Amy ParrA discovery-style experiment is described to enable introductory chemistry students to determine the pressure versus volume behavior of a gas over a wide pressure range to "discover" Boyle's Law. Richmond, Thomas G.; Parr, Amy. J. Chem. Educ.1997, 74, 414.

Gases |

Laboratory Equipment / Apparatus

Sensitivity to Experimental Parameters via SpreadsheetsB. R. SundheimIn spreadsheet computations wherever the functional dependence of calculated results on experimental quantities is obscure, sensitivities may be obtained by testing the effects of variations in relevant inputs. An example is given where Hess' law is explored calorimetrically.Sundhein, B. R. . J. Chem. Educ.1997, 74, 328.

Chemometrics

Stoogiometry: A Cognitive Approach to Teaching StoichiometryCarla R. KriegerMoe's Mall is a locational device designed to be used by learners as a simple algorithm for solving mole-based exercises efficiently and accurately. The mall functions as a map for setting up solutions to mole-based exercises using dimensional analysis. It clears the cognitive decks of students' easily overburdened short-term memory space, allowing them to focus on the versatility of the mole, rather than stepwise solutions to meaningless exercises. Krieger, Carla R. J. Chem. Educ.1997, 74, 306.

Learning Theories |

Computational Chemistry |

Stoichiometry

A Simple Boyle's Law ExperimentDon L. LewisStudent-conducted experiments over a range of pressures from about 14 psi to about 120 psi can safely and accurately be made utilizing a 60 ml syringe and an ordinary bathroom scale. No pressure gauge is required and no value for initial pressure in the syringe (near atmospheric pressure) need be assumed. Lewis, Don L. J. Chem. Educ.1997, 74, 209.

Egg in the Bottle (2)Moran, MichaelThe cause of the pressure drop in the bottle is due to the cooling of high-temperature gases.Moran, Michael J. Chem. Educ.1996, 73, A189.

Gases

Egg in the Bottle (1)DeLorenzo, RonaldThe cooling of gas and the condensation of water vapor must be considered in addition to the loss of oxygen in reducing the pressure inside the glass bottle.DeLorenzo, Ronald J. Chem. Educ.1996, 73, A188.

Gases

The Use of PTFE Membranes for the Construction of Semimicroscale Gas ReactorsSchallies, Michale; Schnelle, Hans-Otto; Kunze, KlausThe membranes are employed to separate reaction compartments, where gas-evolving reactions take place, from solutions of reagents needed for qualitative or quantitative determinations of the gases. The PTFE membranes allow free flow of gases while they prevent the passage of water.Schallies, Michale; Schnelle, Hans-Otto; Kunze, Klaus J. Chem. Educ.1996, 73, A128.

Gases |

Qualitative Analysis |

Quantitative Analysis |

Laboratory Equipment / Apparatus |

Microscale Lab

How Do I Balance Thee? ... Let Me Count the Ways!Lawrence A. FergusonThe author suggests that this would be a good equation for students to try to balance by trial and error because it has two different sets of coefficients that are not multiples of each other. Ferguson, Lawrence A. J. Chem. Educ.1996, 73, 1129.

Stoichiometry

Notes on Vapor Pressure Equilibria MeasurementsAlbert G. Krieger, John W. HendersonFreshman students at our institution use manometers and 24/40 ground-glass distillation apparatus (abandoned by our organic chemistry classes) to measure boiling points at reduced pressures. We have found that the availability of state-of-the-art equipment need not limit the ability to teach and demonstrate fundamental principlesKrieger, Albert G.; Henderson, John W. J. Chem. Educ.1996, 73, 1039.

Gases |

Physical Properties

Oxygen from Hydrogen Peroxide: An Experimental ModificationJames H. Burness This paper describes a simple modification to the generation of oxygen gas experiment which eliminates the need for a pencil coated with petroleum jelly and dry yeast. This elimination not only prevents falling pieces of yeast from prematurely starting the reaction, but at the same time makes the reaction faster and simplifies cleanup.J. Chem. Educ.1996, 73, 851.

Laboratory Equipment / Apparatus |

Gases |

Microscale Lab

A Simple and Low-Cost Air SamplerSashi Saxena Ratna and Pramrod UpadhyayIn this article, an air sampler kit is presented that can be assembled from locally available household materials. The reliability of the sampler kit is also established.Ratna, Shashi Saxena; Upadhyay, Pramod. J. Chem. Educ.1996, 73, 787.

SIRS: Simulations and Interactive Resources, IIIMartin, John S.Simulations and Interactive Resources (SIRs) are designed to support interactive lectures in introductory chemistry. This third issue of SIRs includes five new SIRs as well as updated and final versions of all previously published SIRs.Martin, John S. J. Chem. Educ.1996, 73, 722.

Periodicity / Periodic Table |

Equilibrium |

Gases |

Thermodynamics |

Reactions |

Electrochemistry |

Kinetics

An Approach to Reaction Thermodynamics through Enthalpies, Entropies, and Free Energies of AtomizationJames N. Spencer, Richard S. Moog, and Ronald J. GillespieAn alternative to the conventional method of calculating enthalpies of reaction is presented, using enthalpies of atomization in place of enthalpies of formation. This allows the student to see directly that the reaction enthalpies are determined by the difference in bond strengths in the reactants and products.James N. Spencer, Richard S. Moog, and Ronald J. Gillespie. J. Chem. Educ.1996, 73, 631.

Calorimetry / Thermochemistry |

Thermodynamics |

Equilibrium |

Reactions |

Atomic Properties / Structure |

Stoichiometry

A Novel Approach to Teaching Electrochemical PrinciplesPaul Krause and Jerry ManionTo demonstrate that work may be done by a chemical reaction, a reaction producing a gas is carried out in a large, closed syringe. As the gas is generated, the syringe plunger is forced out.Krause, Paul; Manion, Jerry. J. Chem. Educ.1996, 73, 354.

What's a Mole for?Sheryl DominicA classroom competition for guessing the number of jelly beans in a jar of candy is used to help students understand the premise of the mole concept: counting particles by weighing. Dominic, Sheryl. J. Chem. Educ.1996, 73, 309.

Stoichiometry

Curve Fitting: An Alternative Approach to Analyzing Kinetic Data in Introductory ChemistryColeman, William F.183. The availability of high quality software for performing nonlinear curve fitting on microcomputers allows students to take an alternative approach to data analysis, one that concentrates on functional forms that may be more natural than some of the algebraic machinations necessary to render relationships into linear forms. An example of the application of such an approach to the analysis of kinetic data is presented in this paper.Coleman, William F. J. Chem. Educ.1996, 73, 243.

Chemometrics |

Kinetics

Significant Figures in Graph InterpretationDonald M. GrahamA means is derived for calculating the number of significant figures in the slope and intercept of an experimental linear graph. The method is based on the actual scatter in the points rather than on the nominal precision in the original data, and it can be used even by students who are mathematically fairly unsophisticated. Graham, Donald M. J. Chem. Educ.1996, 73, 211.

Chemometrics

Reinforcing Net Ionic Equation Writing: Second SemesterBetty J. WruckIt is important to actively illustrate that total and net ionic equation writing is a way of learning and expressing an enormous amount of chemistry. There is a major problem with students retaining their ability to write net ionic equations in the second semester. We start this semester with a review and a special, long range assignment. Wruck, Betty J. J. Chem. Educ.1996, 73, 149.

The Environmental Chemistry of Trace Atmospheric GasesWilliam C. TroglerInformation regarding the composition of trace gases in the Earth's atmosphere, changes in these amounts, their sources, and potential future impact on the environment.Trogler, William C. J. Chem. Educ.1995, 72, 973.

Those Baffling SubscriptsArthur W. Friedel and David P. MaloneyStudy of the difficulties students have in interpreting subscripts correctly and distinguishing atoms from molecules when answering questions and solving problems.Friedel, Arthur W.; Maloney, David P. J. Chem. Educ.1995, 72, 899.

The Tube-in-Tube Solution for Gas GenerationArnaiz, Francisco J.Simple apparatus using a magnetic stir bar for adding a liquid reactant to a solid when the volume of the gas produced by the reaction must be determined.Arnaiz, Francisco J. J. Chem. Educ.1995, 72, 572.

A Graphical Representation of Limiting ReactantPhillips, J. C.The concept of limiting reactant may be conveniently illustrated by a graphical representation method that is based on a "minimum slope".Phillips, J. C. J. Chem. Educ.1994, 71, 1048.

Solving equilibria problems with a graphing calculator: A robust method, free of algebra and calculus Ruch, David K.; Chasteen, T. G.The method of successive approximations is frequently introduced in freshman chemistry as a means for solving equilibrium equations. However, this often requires an understanding of calculus that is problematic for introductory chemistry students. An alternative method to solving such equations is to use graphic calculators to solve problems graphically.Ruch, David K.; Chasteen, T. G. J. Chem. Educ.1993, 70, A184.

A new use for the candle and tumbler mythPeckham, Gavin D.In the time it takes to complete the popular but lengthy steel-wool experiment, this author proposes an activity that can be done to add an extra dimension to analyzing oxygen content. This combination of "good" and "bad" experiments proves to be a powerful pedagogical tool.Peckham, Gavin D. J. Chem. Educ.1993, 70, 1008.

Quantitative Analysis |

Atmospheric Chemistry |

Oxidation / Reduction

How thick/thin is your mirror?McCullough, Thomas; Bell, LisaWhen a student reported that his/her water film was 6 cm thick, these authors felt a review of significant figures and dimensional analysis may be in order.McCullough, Thomas; Bell, Lisa J. Chem. Educ.1993, 70, 851.

Chemometrics

A simple demonstration of the law of combining volumes DuPre, Donald B.This demonstration is based on the reaction of two volumes of nitric oxide reacting with one volume of molecular oxygen to produce two volumes of nitrogen dioxide.DuPre, Donald B. J. Chem. Educ.1993, 70, 849.

Gases

Measurement scales: Changing Celsius to Kelvin is not just a unit conversion Nordstrom, Brian H.The key to understanding the difference between Celsius and Kelvin lies in the different types of measurement scales. Students may have an easier time manipulating equations (such as gas laws) if they knew the difference between these scales.Nordstrom, Brian H. J. Chem. Educ.1993, 70, 827.

Unknown identification by simple stoichiometryMcCullough, ThomasA simple experiment in which the student can determine the identity of a soluble carbonate salt using one straightforward reaction and gravimetric analysis.McCullough, Thomas J. Chem. Educ.1993, 70, 592.

A mole of M&M's Merlo, Carmela; Turner, Kathleen E.Engaging students by asking the question: How thick would the layer of M&M candies be if we covered the continental United States with a mole of these candies? Compare this to a mole of water.Merlo, Carmela; Turner, Kathleen E. J. Chem. Educ.1993, 70, 453.

Revealing the secret of the Arctic bomb Pearson, Earl F.Arctic bombs and hurricanes can appear to be contradictory to gas law concepts commonly taught to chemistry students. While these phenomena can be explained as applications of simple gas laws, the explanations can be more effective if an apparent contradiction is drawn between students' understanding and the observed pressure-temperature relationship in these two examples.Pearson, Earl F. J. Chem. Educ.1993, 70, 315.

Measuring Avogadro's number on the overhead projector Solomon, Sally; Hur, ChinhyuA Petri dish filled with water and stearic acid dissolved in petroleum ether upon an overhead projector can be used to introduce the topic of Avogadro's number.Solomon, Sally; Hur, Chinhyu J. Chem. Educ.1993, 70, 252.

An Investigative Density Experiment Samsa, Richard A.A laboratory exercise about density that is engaging and allows students to use higher-level thinking skills and develop a plan to solve a problem.Samsa, Richard A. J. Chem. Educ.1993, 70, 149.

Laboratory Computing / Interfacing |

Chemometrics |

Physical Properties

More on the Question of Significant FiguresClase, Howard J.Because so many students have a hard time understanding what significant figures are all about, this author developed a method using "?" to substitute for insignificant zeros. This helps many students finally grasp this convention.Clase, Howard J. J. Chem. Educ.1993, 70, 133.

Chemometrics

Equilibrium CalculatorAllendoerfer, RobertThe equilibrium calculator can calculate the equilibrium concentrations of all reagents in an arbitrary chemical reaction with as many as five reactants and products.Allendoerfer, Robert J. Chem. Educ.1993, 70, 126.

Is Dimensional Analysis the Best We Have to Offer?Canagaratna, Sebastian G.Dimensional analysis is a unit based approach while the alternative, "method of equations" is a relations-based approach to solving mathematical problems. The author argues that quantitative chemistry involves relationships between quantities and not units, making the later method more pedagogically sound.Canagaratna, Sebastian G. J. Chem. Educ.1993, 70, 40.

Determining the thermal expansion coefficient of gasesLehmann, Jochen K.The authors improved the design of the apparatus and extended the experimental task on a recently published experiment for determining the zero point of the absolute temperature scale.Lehmann, Jochen K. J. Chem. Educ.1992, 69, 943.

On the chemically impossible "other" roots in equilibrium calculations, IILudwig, Oliver G.In a previous paper the author described, using mathematics accessible to students, how an equilibrium calculation leading to a quadratic equation may be shown to have but one "chemical" root. The present work extends this demonstration to some reactions leading to cubic equations.Ludwig, Oliver G. J. Chem. Educ.1992, 69, 884.

Fast molecular motionKnox, KerroA demonstration that shows that molecules do indeed move very fast and over long distances in a short time when nothing is in the way.Knox, Kerro J. Chem. Educ.1992, 69, 574.

A simple generator for common gases at atmospheric pressureElsworth, John F.The current high cost of either a Kipps generator for producing hydrogen sulfide in the undergraduate laboratory, or of the bottled gas, led the writer to construct a simple, economical and efficient generator for use in a laboratory fitted with an efficient fume hood.Elsworth, John F. J. Chem. Educ.1992, 69, 419.

Gases |

Laboratory Equipment / Apparatus

Gas chamber stoichiometry Hunter, Norman W.; Wilkins, Curtis C.; Pearson, Earl F.Most students know that HCN is used in gas chambers, they may not know however that HCN is produced in the burning of carpets, draperies, clothing and other textiles made of polyacrylonitrile.Hunter, Norman W.; Wilkins, Curtis C.; Pearson, Earl F. J. Chem. Educ.1992, 69, 389.

Stoichiometry |

Gases |

Applications of Chemistry

Vapor pressure demonstrations using a butane lighterDelumyea, R. DelThe concept of the change of state of matter and particularly the volatitlity of liquids is an important concept taught in introductory chemistry courses.Delumyea, R. Del J. Chem. Educ.1992, 69, 321.

Balancing a chemical equation: What does it mean?Filgueiras, Carlos AStudents were puzzled by the idea that one chemical equation could be balanced in several different ways. This led to a fruitful discussion on how exact a science chemistry really is.Filgueiras, Carlos A J. Chem. Educ.1992, 69, 276.

An "egg-splosive" demonstration.Becker, Robert.The following demonstration uses an egg to demonstrate the explosive power of a combustible gaseous mixture.Becker, Robert. J. Chem. Educ.1992, 69, 229.

Gases

Are moles really necessary?McCullough, Bro. ThomasMoles should not be allowed to divert ones attention from the equally valid and equally important balanced equation.McCullough, Bro. Thomas J. Chem. Educ.1992, 69, 121.

Stoichiometry

Demonstrations with red cabbage indicator Fortman, John J.; Stubbs, Katherine M.This paper extends the use of the red cabbage extract into demonstrations that illustrate the acidic or basic nature of solutions of gases and gives suggestions for modifications to project the beautiful range of colors and shades for better viewing in large lecture halls.Fortman, John J.; Stubbs, Katherine M. J. Chem. Educ.1992, 69, 66.

Does a one-molecule gas obey Boyle's law?Rhodes, GailBecause the kinetic molecular theory provides a plausible explanation for the lawful behavior of gases, it should be treated in enough depth to show students that the theory accounts for all of the important aspects of ideal gas behavior.Rhodes, Gail J. Chem. Educ.1992, 69, 16.

A mole mnemonicBrown, Bernard S.This article features a chart that provides a fun mnemonic offered to help students struggling with the concept of the mole by making ideas more concrete.Brown, Bernard S. J. Chem. Educ.1991, 68, 1039.

Use of liquid oxygen to support combustion Sullivan, Dan M.Production, procedure, and safety of demonstrations involving liquid nitrogen in order to demonstrate: Charles' Law, production and properties of liquid oxygen, effects of concentration on reactions and reaction rates, liquefaction and boiling of oxygen kindling temperature, reactions between substances in two different states of matter, and comparison of partial and complete combustion.Sullivan, Dan M. J. Chem. Educ.1991, 68, 1036.

Chemical equations are actually matrix equationsAlberty, Robert A.Chemists tend to think that chemical equations are unique to chemistry and they are not used to thinking of chemical equations as the mathematical equations they in fact are. The objective of this paper is to illustrate the mathematical significance of chemical equations.Alberty, Robert A. J. Chem. Educ.1991, 68, 984.

A BASIC program for computing reactant combinations from approximate elemental analysis dataSenthilkumar, Udayampalayam P.; Vijayalakshmi, Rajagopalan; Jeyaraman, Ramasubbu129. A computer program has been developed for determining the number of moles of reactants participating in a reaction in addition to calculating the molecular formula for the analytical data.Senthilkumar, Udayampalayam P.; Vijayalakshmi, Rajagopalan; Jeyaraman, Ramasubbu J. Chem. Educ.1991, 68, 773.

Chemical equilibrium: III. A few math tricks Gordus, Adon A.The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.Gordus, Adon A. J. Chem. Educ.1991, 68, 291.

Finding largest common factors and simplest integer ratios Macomber, Roger S.General chemistry students can ease some of their math-phobia with an exam question that deals with a familiar topic prior to putting these same mathematical principles into the context of chemistry.Macomber, Roger S. J. Chem. Educ.1991, 68, 42.

Accuracy of measurements and the U.S. CensusGorin, GeorgeSome aspects of taking the Census can help students to understand the problem of measurement error and the use of significant figures.Gorin, George J. Chem. Educ.1990, 67, 936.

A miniature hot air balloon and Charles's lawDeese, William C.Heating the air in a tissue paper balloon using a Merker burner and flying it up and down a guided wire in the classroom.Deese, William C. J. Chem. Educ.1990, 67, 672.

Copper dissolution in nitric acid Stairs, Robert A.Previous correspondence on the stoichiometry of the dissolution of copper in nitric acid is confused as a result of the attempt to write a single equation.Stairs, Robert A. J. Chem. Educ.1990, 67, 184.

A proposition about the quantity of which mole is the SI unitRocha-Filho, Romeu C.In this note, after a brief review of the evolution of the meaning of the term mole and a discussion of intrinsic properties of matter, it is proposed that the quantity measured using the SI base unit mole is numerousness, an intrinsic property of samples of matter.Rocha-Filho, Romeu C. J. Chem. Educ.1990, 67, 139.

Stoichiometry

Hot stellar molesMartin, John S.To reinforce elemental concepts of chemistry, it helps to see how they work under unusual conditions.Martin, John S. J. Chem. Educ.1990, 67, 138.

The absorption of UV light by ozone Koubek, EdwardUsing a low-pressure mercury vapor UV lamp and a recently laundered white cotton sheet as a background, one can produce a shadowgraph of ozone emerging from an ozonator.Koubek, Edward J. Chem. Educ.1989, 66, 338.

Overall chemical equationsGil, Victor M. S.An equation sum can be used safely by itself in stoichiometric and equilibrium calculations only if the intermediates produced in separate reactions are at low steady-state concentrations and if there are no other equilibria involving those species.Gil, Victor M. S. J. Chem. Educ.1989, 66, 324.

Moles, pennies, and nickelsMyers. Thomas R.Students frequently have difficulty with the mole concept initially because atoms and molecules are involved and these are invisible.Myers. Thomas R. J. Chem. Educ.1989, 66, 249.

Stoichiometry

Accurate equations of state in computational chemistry projectsAllbee, David; Jones, Edward101. This article presents one method that allows students to become familiar with the use of modern equations of state and also enhances their understanding of how computers can be used in the study and application of chemistry. [Includes "Editor's note: Changes in the computer series", by Lagowski, J. J., p. 226]Allbee, David; Jones, Edward J. Chem. Educ.1989, 66, 226.

Applications of Chemistry |

Chemometrics

A question of basic chemical literacy? Missen, Ronald W.; Smith, William R.The ability to read and write clearly in chemical-equation terms is not as well developed as it should be. The purpose of this "Provocative Opinion" is to draw attention to this problem, and to suggest specific remedies for its solution.Missen, Ronald W.; Smith, William R. J. Chem. Educ.1989, 66, 217.

Teaching stoichiometry: A two cycle approach Poole, Richard L.It is the intent of this article to describe and illustrate a tandem approach for the teaching of stoichiometry that the author developed.Poole, Richard L. J. Chem. Educ.1989, 66, 57.

Analysis of kinetic data with a spreadsheet programHenderson, JohnAn article about spreadsheet templates that accept concentration versus time data for several runs of an experiment, determination of least-squares lines through data points for each run, and will allow the user to exclude points from the least-squares calculation.Henderson, John J. Chem. Educ.1988, 65, A150.

Chemometrics |

Laboratory Computing / Interfacing |

UV-Vis Spectroscopy |

Rate Law |

Kinetics |

Enzymes

Questions from a can of PepsiMitchell, TonyA can of Pepsi can be the starting point of countless chemistry questions that students can relate to. The author encourages other instructors to think about helping students understand chemistry as it relates to contemporary society.Mitchell, Tony J. Chem. Educ.1988, 65, 1070.

Consumer Chemistry |

Applications of Chemistry |

Stoichiometry |

Physical Properties |

Food Science |

Nutrition |

Gases |

Acids / Bases |

Metals

Teaching stoichiometry Figueira, Alvaro RochaStudents have a hard time with stoichiometry because it is often presented in a manner that is divorced from content and application.Figueira, Alvaro Rocha J. Chem. Educ.1988, 65, 1060.

Let's separate theories from calculations Freilich, Mark B.This author writes in a 'provocative opinion' article challenging the readers to think about heavily emphasizing 'thought problems' in chemistry and allowing students to master those before throwing calculations into the mix.Freilich, Mark B. J. Chem. Educ.1988, 65, 442.

Chemometrics

An alternative to using the PV = nRT equation Desmarais, GeorgeThis author shares his application of the factor-label method to solving gas problems which involves using the ideal gas constant as the starting point in the relationship.Desmarais, George J. Chem. Educ.1988, 65, 392.

A multi-topic problem for general chemistry Burness, James H.A 'marathon' problem which requires specific knowledge in several areas while requiring that the student recognize how these areas are related.Burness, James H. J. Chem. Educ.1988, 65, 145.

Good numerical technique in chemistry: The quadratic equationThompson, H. BradfordTexts commonly avoid examples with bad round-off problems or handle them by approximation; none of this is necessary, for simple techniques are available to handle quadratic equations easily and precisely.Thompson, H. Bradford J. Chem. Educ.1987, 64, 1009.

An aqueous problem with an interesting solutionThomas, Nicholas C.Flow diagram outlining the steps to calculating the number of water molecules in one drop of water and the length of all these molecules stretched end to end.Thomas, Nicholas C. J. Chem. Educ.1987, 64, 611.

Control of variables and the conservation of matterGiachino, Gary G.Demonstrates the conservation of matter, but its main value lies in its illustration of the need to control variables and the difficulty this may entail - particularly if a variable is "hidden"; uses a burning candle in a glass flask.Giachino, Gary G. J. Chem. Educ.1987, 64, 353.

Mole fraction revisitedMancott, A.This problem requires the use of algebraic reasoning to derive and solve a fraction linear equation based on the concept of moles and conservation of moles.Mancott, A. J. Chem. Educ.1987, 64, 320.

Election results and reactions yieldsRocha-Filho, Romeu C.Reactions do not always proceed to products as expected from the stoichiometry; sometimes only a fraction of the reagents undergo reaction, while at other times, side products are formed due to competing reactions.Rocha-Filho, Romeu C. J. Chem. Educ.1987, 64, 248.

Stoichiometry

A new method to balance chemical equationsGarcia, ArcesioA simple method, applicable to any kind of reaction, that does not require the knowledge of oxidation numbers.Garcia, Arcesio J. Chem. Educ.1987, 64, 247.

Teaching stoichiometry Steiner, Richard P.This author targets some of the reasons behind why it is so difficult for beginning chemistry students to understand stoichiometry. He reveals that if taught correctly and effectively, a 7-year old can grasp the concepts of stoichiometry.Steiner, Richard P. J. Chem. Educ.1986, 63, 1048.

Is volume conserved?: A first general chemistry experimentOlmsted, John, III.The author presents an experiment that introduces students to scientific methodology, affords practice in the essential laboratory skill of management, and illustrates some fundamental chemical relationships without requiring any chemical sophistication.Olmsted, John, III. J. Chem. Educ.1986, 63, 538.

Gases

What can we do about Sue: A case study of competenceHerron, J. Dudley; Greenbowe, Thomas J.A case study of a "successful" student who is representative of other successful students that are not prepared to solve novel problems.Herron, J. Dudley; Greenbowe, Thomas J. J. Chem. Educ.1986, 63, 528.

Where did that number come from? DeLorenzo, RonaldWith more careful labeling and handling of numbers, instructors can reduce the confusion students sometimes feel when watching problems being solved by the instructor on the board.DeLorenzo, Ronald J. Chem. Educ.1986, 63, 514.

Chemometrics |

Nomenclature / Units / Symbols

Name that compound Mancott, A.These two problems require the use of algebraic reasoning and the application of the concepts of moles, atomic weights, and formulas-these are important facets of the general chemistry course.Mancott, A. J. Chem. Educ.1986, 63, 413.

Mathematics in the chemistry classroom. Part 2. Elementary entities play their partDierks, Werner; Weninger, Johann; Herron, J. DudleyOne of the problems that learners have to overcome when doing stoichiometry calculations is to learn how statements about elementary entities given by formulas and equations are related to statements about portions of substances as measured in the macroscopic world.Dierks, Werner; Weninger, Johann; Herron, J. Dudley J. Chem. Educ.1985, 62, 1021.

Interstellar chemistryCarbo, R.; Ginebreda, A.Surveys some of the features that characterize interstellar chemistry, particularly the composition of the interstellar medium and the nature of the changes that occur there.Carbo, R.; Ginebreda, A. J. Chem. Educ.1985, 62, 832.

The mole: Questioning format can make a differenceLazonby, John N.; Morris, Jane E.; Waddington, David J.Study of 2,695 high school students that found that it is the piecing together of the individual steps involved in mole calculations that presents the main difficulty for students.Lazonby, John N.; Morris, Jane E.; Waddington, David J. J. Chem. Educ.1985, 62, 60.

Nomenclature / Units / Symbols |

Stoichiometry

A LAP on moles: Teaching an important conceptIhde, JohnThe objective of the Learning Activity Packet on moles include understanding the basic concept of the mole as a chemical unit, knowing the relationships between the mole and the atomic weights in the periodic table, and being able to solve basic conversion problems involving grams, moles, atoms, and molecules. [Debut]Ihde, John J. Chem. Educ.1985, 62, 58.

The factor-label method: Is it all that great?Navidi, Marjorie H.; Baker, A. DavidThe development of reasoning skills in chemistry is better achieved by postponing the introduction of the factor-label method.Navidi, Marjorie H.; Baker, A. David J. Chem. Educ.1984, 61, 522.

Composition of gas hydrates. New answers to an old problemCady, George H.The author provides a discussion on nonstoichiometric crystalline solids as they deserve attention in elementary chemistry courses because they are interesting and increasingly important. Laboratory activities are included.Cady, George H. J. Chem. Educ.1983, 60, 915.

Boyle's law experimentHermens, Richard A.This experiment regarding Boyle's law adheres to qualifications which allow the experiment to be meaningful to the students, is safe and simple to perform, low in cost, easy to set up and maintain, obtains reproducible results, and is capable of being performed in a reasonable length of time.Hermens, Richard A. J. Chem. Educ.1983, 60, 764.

Reflections upon mathematics in the introductory chemistry courseGoodstein, Madeline P.It is the purpose of this paper to call attention to the lack of mathematical competence by chemistry students and to invite consideration of one conceptual scheme which may be used to unify the mathematical approach.Goodstein, Madeline P. J. Chem. Educ.1983, 60, 665.

NH4HC03: a stimulant for learningRichards, R. RonaldStudents, professors, and the literature have all been confused by the unusual dissociation equilibrium of NH4HCO3.Richards, R. Ronald J. Chem. Educ.1983, 60, 555.

Equilibrium |

Amines / Ammonium Compounds |

Gases

On the chemically impossible "other" roots in equilibrium problemsLudwig, Oliver G.Students often have a hard time knowing when to disregard equilibrium roots that are too large or are negative. The author suggests a convincing proof that helps students understand how the relationship between the conceptual and mathematical.Ludwig, Oliver G. J. Chem. Educ.1983, 60, 547.

Equilibrium |

Chemometrics

Empirical pKb and pKa for nonmetal hydrides from periodic table positionBayless, Philip L.The equation in this article was developed by the author. It estimates the aqueous pKa for certain acids to an average deviation of 0.1pK unit for those with experimentally determined values and agrees with experimentally determined values, and as well as with estimates for those too weak or too strong to be measured.Bayless, Philip L. J. Chem. Educ.1983, 60, 546.

Acids / Bases |

pH |

Chemometrics

Le Châtelier's principle: the effect of temperature on the solubility of solids in liquidsBrice, L. K.The purpose of this article is to provide a rigorous but straightforward thermodynamic treatment of the temperature dependence of solubility of solids in liquids that is suitable for presentation at the undergraduate level. The present discussion may suggest how to approach the qualitative aspects of the subject for freshman.Brice, L. K. J. Chem. Educ.1983, 60, 387.

Thermodynamics |

Liquids |

Solids |

Chemometrics |

Equilibrium

Estimating energy outputs of fuelsBaird, N. ColinWhich is the best fuel in terms of heat energy output: coal, natural gas, fuel oil, hydrogen, or alcohol? It is possible to obtain a semi quantitative estimate of the heat generated by combustion of a fuel from the balanced chemical equation alone.Baird, N. Colin J. Chem. Educ.1983, 60, 356.

Mass spectral analysis of halogen compounds Holdsworth, David K.37. Bits and pieces, 14. A pocket calculator can be programmed to decide and display the halogen combination in a molecular-ion cluster by examination of the (M+2)/M or (X+2)/X percentage values.Holdsworth, David K. J. Chem. Educ.1983, 60, 103.

An effective demonstration of some properties of real vaporsMetsger, D. ScottThe apparatus described in this article has been found by the authors to be the most effective in vividly illustrating the behavior of a nearly ideal gas to first year chemistry students.Metsger, D. Scott J. Chem. Educ.1983, 60, 67.

Boyle's law - A different viewSharma, B. D.For a fixed mass of gas at constant temperature the energy of the gas is fixed and independent of its pressure and volume.Sharma, B. D. J. Chem. Educ.1982, 59, 827.

Mathematics in data analysis: An introductionWang, TaitzerThe meaning of simple mathematical equations are described in a perspective that, for some reasons, many beginning students do not seem to be able to obtain from reading textbooks on the subject.Wang, Taitzer J. Chem. Educ.1982, 59, 592.

Think Wheeler, S. J., James D.Students have an easy enough time crunching numbers, but it is alarming how little they understand the concepts behind the numbers. Students should not be making remarks such as, "If they keep changing how they write the problems, how am I supposed to know how to solve them?"Wheeler, S. J., James D. J. Chem. Educ.1981, 58, 1004.

Bad booze O'Connor, RodOne of the brain tinglers: What is the maximum volume of 95% ethanol that a 120lb student could consume to reach a potentially lethal dosage of alcohol? This tingler also helps students understand why it is important to have denatured alcohol in the lab.O'Connor, Rod J. Chem. Educ.1981, 58, 502.

Alcohols |

Toxicology |

Stoichiometry |

Applications of Chemistry

Pressure and the exploding beverage container Perkins, Robert R.The question in this article is an extension of exploding pop bottles to illustrate the balancing of a chemical equation, enthalpy, stoichiometry, and vapor pressure calculations, and the use of the Ideal Gas Equation. The question is aimed at the first-year level student.Perkins, Robert R. J. Chem. Educ.1981, 58, 363.

An experimental introduction to stoichiometry Webb, Michael J.A procedure for an experiment with the purpose: To show via experiment that the quantities of materials used in chemical reactions are related to balanced chemical equations.Webb, Michael J. J. Chem. Educ.1981, 58, 192.

Empirical formulas - A ratio problemKnox, KerroA problem involving an analogy between ratios of boys to girls given their average weights and percentage composition of the class by weight.Knox, Kerro J. Chem. Educ.1980, 57, 879.

Chemometrics |

Molecular Properties / Structure

An approximate determination of Avogadro's constantSzll, Thomas; Dennis, David; Jouas, Jean-Pierre; Wong, MabelAn experiment to determine a value for Avogadro's number by determining the relationship between the number of electrons flowing through an acidified solution of water and the number of moles of electrons which reduce hydrogen ions to produce hydrogen gas.Szll, Thomas; Dennis, David; Jouas, Jean-Pierre; Wong, Mabel J. Chem. Educ.1980, 57, 735.

A chemistry lesson at Three Mile IslandMammano, Nicholas J.Teaching principles of general chemistry through references made to the nuclear incident at Three Mile Island.Mammano, Nicholas J. J. Chem. Educ.1980, 57, 286.

Ga(U)Ge pressure and absolute pressureDavenport, Derek A.Air is progressively removed from a test tube; the pressure inside is measured using a standard tire-pressure gauge that is found to read atmospheric pressure when the test tube is fully evacuated.Davenport, Derek A. J. Chem. Educ.1979, 56, 322.

Gases

Boyle's lawDavenport, Derek A.Increasing weights are placed on a sealed syringe, compressing the air inside, and increasing weights pull the plunger from a held syringe, expanding the air inside. In both cases, plots of "P" vs. V are recorded.Davenport, Derek A. J. Chem. Educ.1979, 56, 322.

Evolution of an experiment (from moles/I2 to gaseous CaCl2)Dauphinee, G. A.An experiment originally designed to illustrate a simple problem in solution stoichiometry has produced a stimulus to student recognition of some applications of descriptive chemistry.Dauphinee, G. A. J. Chem. Educ.1979, 56, 116.

Stoichiometry |

Descriptive Chemistry

A discovery experiment. CO2 soap bubble dynamicsMillikan, Roger C.Students often make a choice of major based upon the view of a subject that they derive from the beginning course. Rare are the chemistry courses that provide the excitement and chance for discovery, while providing a basic understanding of chemistry. This article describes an experiment that does provide such an opportunity.Millikan, Roger C. J. Chem. Educ.1978, 55, 807.

Intuitive and general approach to acid-base equilibrium calculationsFelty, Wayne L.The purpose of this paper is to show that the usual intuitive approach used in general chemistry can be readily extended without introduction of additional, sophisticated concepts to give the general, exact expression and to point out the pedagogical advantage of its use.Felty, Wayne L. J. Chem. Educ.1978, 55, 576.

Acids / Bases |

Equilibrium |

Chemometrics

Bubble pressure and volume. A demonstration experimentChristian, Sherril D.; Enwall, EricAn interesting phenomenon which illustrates several important principles, is the dependence of the size of a soap bubble on pressure. The subject is introduced to the class by the black box experiment presented in this article.Christian, Sherril D.; Enwall, Eric J. Chem. Educ.1978, 55, 536.

Gases |

Surface Science

Pressure calculations Schultz, Charles W.This question requires students to be able to distinguish two kinds of pressure: Boyles law pressure of gas (that depends on volume) from the equilibrium vapor pressure above a liquid (that does not).Schultz, Charles W. J. Chem. Educ.1978, 55, 515.

Gases |

Chemometrics

Development of intellectual skills in the laboratoryOphardt, Charles E.This first semester laboratory was designed to give instruction and practice in the intellectual skills of application, analysis, synthesis, and in Piaget's formal operations.Ophardt, Charles E. J. Chem. Educ.1978, 55, 485.

Teaching the method of successive approximationsNassiff, Peter J.; Boyko, E. R.The purpose of this papers is to help the teacher show the student why basic methods of successive approximations work, how they may be applied, and under what conditions it will be successful.Nassiff, Peter J.; Boyko, E. R. J. Chem. Educ.1978, 55, 376.

The chemical equation. Part I: Simple reactionsKolb, DorisA chemical equation is often misunderstood by students as an "equation" that is used in chemistry. However, a more accurate description is that it is a concise statement describing a chemical reaction expressed in chemical symbolism.Kolb, Doris J. Chem. Educ.1978, 55, 184.

Stoichiometry |

Chemometrics |

Nomenclature / Units / Symbols |

Reactions

General chemistry-pressure measurement Steffel, Margaret J.This question allows students to demonstrate the understanding of the operation of barometers and vapor pressure at a freshman level.Steffel, Margaret J. J. Chem. Educ.1978, 55, 102.

Great spray can debateBassow, HerbA curriculum scenario that takes the problems raised by the technological, economic, and political contexts of the fluorocarbon controversy as its point of focus.Bassow, Herb J. Chem. Educ.1977, 54, 371.

Simplified Boyle's Law demonstrationMiller, Daniel W.Placing a sealed syringe in bell jar attached to a vacuum pump and reading the volume of air inside the syringe at various reduced pressures.Miller, Daniel W. J. Chem. Educ.1977, 54, 245.

Gases

Le Chtelier's principle: A laboratory exerciseFriedman, FredericaLe Chtelier's principle can be demonstrated by showing that water can boil at temperatures below 100C due to reduced vapor pressure.Friedman, Frederica J. Chem. Educ.1977, 54, 236.

Cookbook dimensional analysisDeLorenzo, RonaldFrequently, teachers will hear, "...it looks easy when you do it..." when teaching dimensional analysis. This teacher advises others on a way to help students gain self-efficacy with this problem solving-strategy.DeLorenzo, Ronald J. Chem. Educ.1976, 53, 633.

Lab safety: The case of the errant cylinder Ozaruk, N.The anchoring of compressed gas cylinders to keep them from being knocked over, with the accompanying possibility of breaking off the valve, is an accepted safe practice. However, there has been some skepticism as to what would have happened if a cylinder valve was knocked off. The author shares a vivid description that appeared in the National Safety Council Chemical Section Newsletter. Also: a high school safety rules booklet; a hazardous materials safety booklet; and wall charts on Laboratory Techniques and Laboratory Safety.Ozaruk, N. J. Chem. Educ.1976, 53, 373.

Maximizing profits in equilibrium processesRish, Ronald J.Provides the student with an example in which both chemical principles and calculus are applied to a realistic industrial situation where profits are a must.Rish, Ronald J. J. Chem. Educ.1975, 52, 441.

An experiment for introductory college chemistry. How to establish a chemistry equationMasaguer, J. R.; Coto, M. Victoria; Casas, J. S.The stoichiometry of the reaction between potassium chromate and barium chloride in an aqueous state is determined by using the height of of the precipitate formed when different amounts of both solutions are mixed in a graduated cylinder.Masaguer, J. R.; Coto, M. Victoria; Casas, J. S. J. Chem. Educ.1975, 52, 387.

Molar solubility calculations and the control equilibriumChaston, S. H. H.The Control-Equilibrium method uses as its starting point a precise procedure for obtaining the equilibrium that accounts for the bulk of the decomposition of starting materials.Chaston, S. H. H. J. Chem. Educ.1975, 52, 206.

A Dalton's law experiment for students in the health sciencesFeigl, Dorothy M.The number of students who take an introductory chemistry course in preparation for the health sciences is increasing. This note is an illustration of Dalton's law of partial pressures adapted to demonstrate the ability of the lungs to effect the removal of excess dioxide from the body.Feigl, Dorothy M. J. Chem. Educ.1974, 51, 273.

Using alligation alternate to solve composition problemsMancott, AnatolProblems involving the composition of mixtures may be solved by using the relatively obscure method of "alligation alternate" in lieu of the standard algebraic procedure with no loss in accuracy; includes five examples.Mancott, Anatol J. Chem. Educ.1972, 49, 57.

Tire Inflation ThermodynamicsPlumb, Robert C.; Connors, John J.Explains why inflating a tire with a hand pump heats the air being pumped into the tire.Plumb, Robert C.; Connors, John J. J. Chem. Educ.1971, 48, 837.

SI units in physico-chemical calculationsNorris, A. C.This article demonstrates how the adoption of SI units affects some of the more important physico-chemical calculations found at the undergraduate level.Norris, A. C. J. Chem. Educ.1971, 48, 797.

Nomenclature / Units / Symbols |

Chemometrics

Bag-assembly for gas experimentGregory, MichaelAn improved bag-assembly has been devised for use with the Chem Study Experiment, "The Weights of Equal Volumes of Gases."Gregory, Michael J. Chem. Educ.1971, 48, 796.

Chemical queries. Especially for introductory chemistry teachersYoung, J. A.; Malik, J. G.; Strong, Laurence E.(1) What evidence, understandable and acceptable to students, do most teachers cite to describe the transfer of charge from one electrode to another in the direct current electrolysis of an electrolyte solution? (2) What is a compound? - answer by Strong. (3) What is a molecule? - answer by Strong.Young, J. A.; Malik, J. G.; Strong, Laurence E. J. Chem. Educ.1970, 47, 523.

Electrochemistry |

Aqueous Solution Chemistry |

Stoichiometry |

Molecular Properties / Structure

Prolonging death (in apples)Plumb, Robert C.Using controlled atmosphere storage to prolong the freshness of vegetables and fruits after they have been harvested.Plumb, Robert C. J. Chem. Educ.1970, 47, 518.

Sealed tube experimentsCampbell, J. A.Lists and briefly describes a large set of "sealed tube experiments," each of which requires less than five minutes to set-up and clean-up, requires less than five minutes to run, provides dramatic results observable by a large class, and illustrates important chemical concepts.Campbell, J. A. J. Chem. Educ.1970, 47, 273.

Thermodynamics |

Crystals / Crystallography |

Solids |

Liquids |

Gases |

Rate Law |

Equilibrium

Cloud Caps on High MountainsStevenson, Philip E.The formation of cloud caps on high mountains illustrates cooling in an adiabatic expansion and the change in vapor pressure of a liquid with temperature.Stevenson, Philip E. J. Chem. Educ.1970, 47, 272.

Atmospheric Chemistry |

Gases |

Applications of Chemistry |

Phases / Phase Transitions / Diagrams |

Thermodynamics

A demonstration experiment on partial molar volumesCoch, Juan A.; Lopez, ValentinThe partial molar volume of trichloroacetic acid can be determined by measuring the increase in volume when TCA is dissolved in water at constant temperature and pressure.Coch, Juan A.; Lopez, Valentin J. Chem. Educ.1970, 47, 270.

Solutions / Solvents |

Molecular Properties / Structure |

Stoichiometry

Environmental chemistry in the classroomDay, Jean W.The environmental sciences is an especially good vehicle for relating chemistry to other disciplines in courses for nonscientists.Day, Jean W. J. Chem. Educ.1970, 47, 260.

Nonmajor Courses |

Atmospheric Chemistry |

Applications of Chemistry

A lecture-laboratory experiment in gas-liquid partition chromatographyMcKay, Edward S.; Vasers, AliseAfter being introduced to the chromatographic process in lecture, each student is given a copy of a chromatogram of an unknown mixture and asked to identify its composition and the concentration of each component.McKay, Edward S.; Vasers, Alise J. Chem. Educ.1970, 47, 239.

Hydrolysis of sodium carbonateNakayama, F. S.Presents a procedure for obtaining the ion concentrations of the various component species produced by the hydrolysis of sodium carbonate.Nakayama, F. S. J. Chem. Educ.1970, 47, 67.

Avogadro's number from the volume of a monolayerMoynihan, Cornelius T.; Goldwhite, HaroldThis article comments on and makes suggestions regarding the conduct of and treatment of data in the popular experiment in which Avogadro's number is estimated from the volume of a monolayer on a water surface.Moynihan, Cornelius T.; Goldwhite, Harold J. Chem. Educ.1969, 46, 779.

An improved equivalent weight apparatusBrown, Oliver L.Presents an improved apparatus for the reaction of weighed samples of metals with hydrochloric acid and the measurement of the volume of hydrogen evolved.Brown, Oliver L. J. Chem. Educ.1969, 46, 617.

Friday experimentsBissey, Jack E.Provides data on an unknown gas and asks readers to determine if it is ideal, as well as its molecular weight and chemical formula.Bissey, Jack E. J. Chem. Educ.1969, 46, 497.

Avogadro's number by four methodsSlabaugh, W. H.Describes a project by two general chemistry students to compare four methods for finding Avogadro's number; this article focusses on the electroplating method.Slabaugh, W. H. J. Chem. Educ.1969, 46, 40.

Chemical queries. Especially for introductory chemistry teachersYoung, J. A.; Malik, J. G.; Bolte, John(1) Is the mole a number or a weight? (2) Is there an easy way to locate a compound by volume and page in Beilstein? (3) What are the stages evident in a gas discharge tube as the pressure of the gas and the voltage are changed? - answer by BolteYoung, J. A.; Malik, J. G.; Bolte, John J. Chem. Educ.1968, 45, 718.

From stoichiometry and rate law to mechanismEdwards, John O.; Greene, Edward F.; Ross, JohnExamines the rules used by chemists as guidelines in developing mechanisms from stoichiometric and rate law observations. Edwards, John O.; Greene, Edward F.; Ross, John J. Chem. Educ.1968, 45, 381.

Structure units: Aids in the interpretation of chemical reactionsStrong, Laurence E.the proposal to define structure units as generators of the various properties of a substance has a considerable advantage over the usual definition of a structure unit as the endpoint of some prescribed scheme of subdivision.Strong, Laurence E. J. Chem. Educ.1968, 45, 51.

The range of validity of Graham's LawsKirk, A. D.It is the purpose of this article to discuss effusion, diffusion, and some related processes and to outline the range of validity of Graham's law.Kirk, A. D. J. Chem. Educ.1967, 44, 745.

Gases |

Transport Properties

Graham's Laws of diffusion and effusionMason, E. A.; Kronstadt, BarbaraThe purpose of this article is to review Graham's laws of diffusion and effusion, offer simple but essentially correct theoretical explanations for both laws, and to present experiments on the diffusion law.Mason, E. A.; Kronstadt, Barbara J. Chem. Educ.1967, 44, 740.

The stoichiometry of an oxidation-reduction reactionLatimer, George W., Jr.A short note on the titration of hydrazine sulfate with standard bromate in the presence of sodium molybdate that requires students to identify the products through the use of some elementary qualitative analysis.Latimer, George W., Jr. J. Chem. Educ.1967, 44, 537.

An experimental approach to the ideal gas lawBreck, W. G.; Holmes, F. W.It is possible to introduce to students the equation of state, PV = nRT, by an experimental method that demonstrates that PV/T remains constant for a given amount of gas.Breck, W. G.; Holmes, F. W. J. Chem. Educ.1967, 44, 293.

The relationship between Avogadro's Principle and the Law of Gay-LussacFeifer, NathanTeaching Avogadro's Principle as an explanation of the phenomena described by Gay-Lussac's Law gives the instructor an opportunity to stress some of the basic assumptions in chemistry and to highlight the logic implicit in Avogadro's reasoning.Feifer, Nathan J. Chem. Educ.1966, 43, 411.

Kinetic energies of gas moleculesAherne, John C.The graph representing the distribution of kinetic energy among the molecules of a gas found in many textbooks is incorrect.Aherne, John C. J. Chem. Educ.1965, 42, 655.

Stoichiometry of the reaction of bromine with phenolsLockwood, Karl L.The purpose of this investigation is to establish the stoichiometry for the reaction of a number of phenols with bromine, and to demonstrate the rapid and quantitative nature of the reaction of bromine with enols.Lockwood, Karl L. J. Chem. Educ.1965, 42, 482.

Determination of Avogadro's number by Perrin's lawSlabaugh, W. H.The experimental procedure for determining Avogadro's number by the Perrin method includes preparing a monodisperse colloid, ascertaining the mass of the particles, and making an accurate count of the number of particles at two points in the equilibrated colloid.Slabaugh, W. H. J. Chem. Educ.1965, 42, 471.

Teaching ionic equilibrium: Use of log chart transparenciesFreiser, Henry; Fernando, QuintusThe use of graphical methods brings the problem of significance of various terms in complicated expressions into proper focus. Furthermore, a pictorial representation permits the student to see at a glance how the concentrations of various species in a system at equilibrium change with conditions.Freiser, Henry; Fernando, Quintus J. Chem. Educ.1965, 42, 35.

Maximum work revisited (Letters)Mysels, Karol J.Comments on an earlier "Textbook Error" article that considers at length errors in the calculation of work done in compression or expansion of an ideal gas.Mysels, Karol J. J. Chem. Educ.1964, 41, 677.

Thermodynamics |

Gases

Maximum work revisited (Letters)Bauman, RobertComments on an earlier "Textbook Error" article that considers at length errors in the calculation of work done in compression or expansion of an ideal gas.Bauman, Robert J. Chem. Educ.1964, 41, 676.

Thermodynamics |

Gases

Maximum work revisited (Letters)Kokes, Richard J.Comments on an earlier "Textbook Error" article that considers at length errors in the calculation of work done in compression or expansion of an ideal gas.Kokes, Richard J. J. Chem. Educ.1964, 41, 675.

Thermodynamics |

Gases

Maximum work revisited (Letters)Bauman, RobertComments on an earlier "Textbook Error" article that considers at length errors in the calculation of work done in compression or expansion of an ideal gas.Bauman, Robert J. Chem. Educ.1964, 41, 675.

The Carnot cycle and Maxwell's relationsNash, Leonard K.Maxwells equations can be derived from nothing more than the Carnot cycle and the deployment of the simplest plane geometry.Nash, Leonard K. J. Chem. Educ.1964, 41, 368.

Thermodynamics |

Chemometrics

Beer's law without calculusPinkerton, Richard C.There is no good reason for using calculus in the presentation of Beer's law.Pinkerton, Richard C. J. Chem. Educ.1964, 41, 366.

Chemometrics

The chemistry of the noble gasesHyman, Herbert H.Summarizes the chemistry of the noble gases and their bond-forming abilities.Hyman, Herbert H. J. Chem. Educ.1964, 41, 174.

Work of compressing an ideal gasBauman, Robert P.In formulating examples of compression problems there should be an explicit statement that the process is reversible, or at least slow.Bauman, Robert P. J. Chem. Educ.1964, 41, 102.

Thermodynamics |

Gases

Demonstration notes: Oxygen in airGlanz, JosephExplains that the popular method of demonstrating the percentage volume of oxygen in air is fraut with errors.Glanz, Joseph J. Chem. Educ.1963, 40, A477.

A simple gas law apparatusCarter, K. N.The apparatus presented here can be used to verify the ideal gas law, determine the vapor pressure of water at an elevated temperature, or determine the number of moles of dry air under two different sets of conditions for comparison.Carter, K. N. J. Chem. Educ.1962, 39, 302.

Dalton's law of partial pressuresDutton, Frederic B.Demonstrates that breaking a sealed ampule of ether in a closed system increases the pressure inside that system.Dutton, Frederic B. J. Chem. Educ.1961, 38, A545.

Gases |

Ethers

LettersCrawford, Crayton M.Comments on use of the term equivalent weights and the determination of equivalent mass.Crawford, Crayton M. J. Chem. Educ.1961, 38, 637.

An approach to complex equilibrium problemsButler, James N.Presents an approach to equilibrium problems that sets up enough equations relating the various concentrations present to define the system completely and then makes approximations that simplify the equations.Butler, James N. J. Chem. Educ.1961, 38, 141.

Equilibrium |

Chemometrics |

Acids / Bases |

Aqueous Solution Chemistry

The mole and related quantitiesGuggenheim, E. A.Examines some of the terminology associated with the mole and expressing amounts of substances.Guggenheim, E. A. J. Chem. Educ.1961, 38, 86.

Stoichiometry |

Nomenclature / Units / Symbols

Editorially speakingKieffer, William K.Calls attention to an article in this issue of the Journal on the mole concept.Kieffer, William K. J. Chem. Educ.1961, 38, 51.

Kinetic molecular theory from a jukeboxEasley, W. K.; Powers, Glenn F.Uses dancers to various styles of music as an analogy for differences between the atomic and molecular motions in solids, liquids, and gases.Easley, W. K.; Powers, Glenn F. J. Chem. Educ.1960, 37, 302.

Kinetic-Molecular Theory |

Solids |

Liquids |

Gases

Vapor pressure determination: An elementary experimentRadley, Edward T.The approximate vapor pressure of low boiling liquids may be estimated by measuring the increase in length of an air column trapped between two short columns of mercury in a uniform diameter tube.Radley, Edward T. J. Chem. Educ.1960, 37, 35.

A test tube automatic gas generatorAlpern, D. K.A simple design for an automatic gas generator can be used to produce common gases such as hydrogen from zinc and hydrochloric acid.Alpern, D. K. J. Chem. Educ.1959, 36, 302.

The hydrogen organEddy, Robert D.The hydrogen organ can be used to demonstrate a variety of physical and chemical properties.Eddy, Robert D. J. Chem. Educ.1959, 36, 256.

Gases

A molality-molarity paradox?Toby, SidneyThe author points out that there seems no obvious reason why molality could not equal molarity in a solution whose density is less than unity.Toby, Sidney J. Chem. Educ.1959, 36, 230.

An exact titration equationBolie, Victor W.The purpose of this paper is to show the development of a titration equation for a precipitation reaction which is exact in the mathematical sense.Bolie, Victor W. J. Chem. Educ.1958, 35, 449.

Radioisotopes on your rooftopLockhart, Luther, B., Jr.The collection, recovery, and measurement of radioactive materials from atomic testing can be done through the use of relatively simple procedures and is a good exercise in tracer chemistry.Lockhart, Luther, B., Jr. J. Chem. Educ.1957, 34, 602.

Letters to the editorGaddis, Shirley W.Has not the time come to bring up for debate the question of the advisability of teaching the equivalent weight concept?Gaddis, Shirley W. J. Chem. Educ.1955, 32, 289.

Gram equivalent weightsMeldrum, William B.The purpose of this paper is to review briefly the subject of equivalent weights and the more directly applicable gram equivalents and to offer a general method by which they may be deduced from chemical equations.Meldrum, William B. J. Chem. Educ.1955, 32, 48.

Le Châtelier's principle and the equilibrium constantMiller, Arild J.Many students of chemistry have difficulty in understanding how the position of equilibrium in a gaseous reaction can change when the pressure is altered, in accordance with Le Châtelier's principle, without causing a corresponding variation in the equilibrium constant.Miller, Arild J. J. Chem. Educ.1954, 31, 455.

Material balances and redox equationsBennett, George W.It is the purpose of this paper to remind teachers of a third method of balancing redox equations that does not depend on rule-of-thumb empiricism but relies on the conservation of matter.Bennett, George W. J. Chem. Educ.1954, 31, 324.

Otis Coe Johnson and redox equationsBennett, George W.It is the purpose of this paper to point out what is basic verity and what is empiricism in Johnson's method for balancing oxidation-reduction equations.Bennett, George W. J. Chem. Educ.1954, 31, 157.

Oxidation / Reduction |

Oxidation State |

Stoichiometry

Determination of the density of oxygen gasFiekers, B. A.The "Oxybomb," a small cartridge of compressed oxygen, is used for determining the density of oxygen gas in laboratory or lecture.Fiekers, B. A. J. Chem. Educ.1954, 31, 139.

Letters to the editorStanden, AnthonyHelping students to understand the experiment they have done is a difficult task; experiments that claim to "prove" physical laws or determine Avogadro's number compound this problem.Standen, Anthony J. Chem. Educ.1954, 31, 46.

LettersNair, C. N.A mathematical derivation demonstrating that masses of different elements equal to their atomic weights must contain the same number of atoms.Nair, C. N. J. Chem. Educ.1953, 30, 155.

Stoichiometry |

Atomic Properties / Structure

The kinetic structure of gasesSlabaugh, W. H.Describes a model that illustrates the kinetic properties of gases and ii use to demonstrate the effect of temperature changes on the motion of gas particles.Slabaugh, W. H. J. Chem. Educ.1953, 30, 68.

Gases |

Kinetic-Molecular Theory |

Phases / Phase Transitions / Diagrams

An experiment on the law of multiple proportionsSecrist, John H.It is suggested that the reduction of cuprous and cupric oxides serves as a satisfactory laboratory demonstration of the law of multiple proportions.Secrist, John H. J. Chem. Educ.1952, 29, 283.

On accenting observations in chemistryCampbell, J. A.A chemical equations is, for many a student, such a complete abstraction that he would be hard put to describe the actual observations that would be made in a process for which he was supplied the complete equation.Campbell, J. A. J. Chem. Educ.1951, 28, 634.

Reactions |

Stoichiometry |

Nomenclature / Units / Symbols

A common misunderstanding of Hess' lawDavis, Thomas. W.The statement, sometimes attributed to Hess, that "In any series of chemical or physical changes the total heat effect is independent of the path by which the system goes from its initial to its final state" is incorrect.Davis, Thomas. W. J. Chem. Educ.1951, 28, 584.

Stoichiometry |

Acids / Bases |

Aqueous Solution Chemistry |

Calorimetry / Thermochemistry

LettersSeeger, WalfriedCommentary on determining the combining weights of zinc or cadmium by dissolving them in HCl or aqua regia.Seeger, Walfried J. Chem. Educ.1951, 28, 397.

Lettersde Milt, ClaraThe author calls for a mnemonic device to assist students in learning the gas laws and points out the omission of Graham's law from a recent textbook.de Milt, Clara J. Chem. Educ.1951, 28, 115.